Dressings for the prevention of surgical site infection

  • Review
  • Intervention

Authors


Abstract

Background

Surgical wounds (incisions) heal by primary intention when the wound edges are brought together and secured, often with sutures, staples, or clips. Wound dressings applied after wound closure may provide physical support, protection and absorb exudate. There are many different types of wound dressings available and wounds can also be left uncovered (exposed). Surgical site infection (SSI) is a common complication of wounds and this may be associated with using (or not using) dressings, or different types of dressing.

Objectives

To assess the effects of wound dressings compared with no wound dressings, and the effects of alternative wound dressings, in preventing SSIs in surgical wounds healing by primary intention.

Search methods

We searched the following databases: the Cochrane Wounds Specialised Register (searched 19 September 2016); the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 2016, Issue 8); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations, MEDLINE Daily and Epub Ahead of Print; 1946 to 19 September 2016); Ovid Embase (1974 to 19 September 2016); EBSCO CINAHL Plus (1937 to 19 September 2016).

There were no restrictions based on language, date of publication or study setting.

Selection criteria

Randomised controlled trials (RCTs) comparing wound dressings with wound exposure (no dressing) or alternative wound dressings for the postoperative management of surgical wounds healing by primary intention.

Data collection and analysis

Two review authors performed study selection, 'Risk of bias' assessment and data extraction independently.

Main results

We included 29 trials (5718 participants). All studies except one were at an unclear or high risk of bias. Studies were small, reported low numbers of SSI events and were often not clearly reported. There were 16 trials that included people with wounds resulting from surgical procedures with a 'clean' classification, five trials that included people undergoing what was considered 'clean/contaminated' surgery, with the remaining studies including people undergoing a variety of surgical procedures with different contamination classifications. Four trials compared wound dressings with no wound dressing (wound exposure); the remaining 25 studies compared alternative dressing types, with the majority comparing a basic wound contact dressing with film dressings, silver dressings or hydrocolloid dressings. The review contains 11 comparisons in total.

Primary outcome: SSI

It is uncertain whether wound exposure or any dressing reduces or increases the risk of SSI compared with alternative options investigated: we assessed the certainty of evidence as very low for most comparisons (and low for others), with downgrading (according to GRADE criteria) largely due to risk of bias and imprecision. We summarise the results of comparisons with meta-analysed data below:

- film dressings compared with basic wound contact dressings following clean surgery (RR 1.34, 95% CI 0.70 to 2.55), very low certainty evidence downgraded once for risk of bias and twice for imprecision.

- hydrocolloid dressings compared with basic wound contact dressings following clean surgery (RR 0.91, 95% CI 0.30 to 2.78), very low certainty evidence downgraded once for risk of bias and twice for imprecision.

- hydrocolloid dressings compared with basic wound contact dressings following potentially contaminated surgery (RR 0.57, 95% CI 0.22 to 1.51), very low certainty evidence downgraded twice for risk of bias and twice for imprecision.

- silver-containing dressings compared with basic wound contact dressings following clean surgery (RR 1.11, 95% CI 0.47 to 2.62), very low certainty evidence downgraded once for risk of bias and twice for imprecision.

- silver-containing dressings compared with basic wound contact dressings following potentially contaminated surgery (RR 0.83, 95% CI 0.51 to 1.37), very low certainty evidence downgraded twice for risk of bias and twice for imprecision.

Secondary outcomes

There was limited and low or very low certainty evidence on secondary outcomes such as scarring, acceptability of dressing and ease of removal, and uncertainty whether wound dressings influenced these outcomes.

Authors' conclusions

It is uncertain whether covering surgical wounds healing by primary intention with wound dressings reduces the risk of SSI, or whether any particular wound dressing is more effective than others in reducing the risk of SSI, improving scarring, reducing pain, improving acceptability to patients, or is easier to remove. Most studies in this review were small and at a high or unclear risk of bias. Based on the current evidence, decision makers may wish to base decisions about how to dress a wound following surgery on dressing costs as well as patient preference.

Plain language summary

Dressings for the prevention of surgical site infection

Review question

This review aimed to assess whether use of different wound dressings (or leaving a wound exposed without a dressing) has an impact on the number of people who get wound infections following surgery where the wound is closed with stitches, staples, clips or glue. We also investigated whether different dressings resulted in less pain, less scarring or were more acceptable to patients and health professionals.

Background

Millions of surgical procedures are conducted globally each year. The majority of procedures result in wounds in which the edges are brought together to heal using stitches, staples, clips or glue; this is called 'healing by primary intention'. Afterwards, wounds are often covered with a dressing that acts as a barrier between it and the outside environment. One possible advantage of a dressing may be to protect the wound from infection (surgical site infection). Many different dressing types are available for use on surgical wounds. However, it is not clear whether one type of dressing is better than any other in preventing surgical site infection, or, indeed, whether it is better not to use a dressing at all.

Study characteristics

We conducted a review of all available, relevant evidence about the impact of dressings on the prevention of surgical site infections in surgical wounds healing by primary intention. This review examined data from 29 randomised controlled trials (which provide the most reliable evidence). These investigated the use of dressings in surgery that had a low risk of surgical site infection (clean surgery) and surgery with a higher risk (potentially contaminated surgery).

Key results

We found no clear evidence to suggest that one dressing type was better than any other at reducing the risk of surgical site infection, nor that covering wounds with any dressing at all reduced the risk of surgical site infection. Additionally, there was no clear evidence that any dressing type improves scarring, pain control, patient acceptability or ease of removal. Currently decision makers may opt to make decisions about whether and how to dress a wound based on patient and clinician preferences and dressing costs.

Certainty of the evidence

It is important to note that many trials in this review were small and the evidence was of low or very low certainty meaning that current information is uncertain.

Assessed as up to date September 2016.

淺顯易懂的口語結論

預防手術部位感染之敷料

文獻回顧問題

本篇文獻回顧旨在評估不同的傷口敷料(或無使用傷口敷料)之使用,是否對於手術後,以縫線,吻合器,縫合夾或是組織膠來癒合傷口而發生傷口感染的人數有影響。我們還調查了不同的敷料是否能減低疼痛,減少疤痕或是更容易被患者和衛生專業人員所接受。

背景

全球每年進行數百萬次的外科手術。大多數因手術而產生的傷口,使用縫線,吻合器,縫合夾或是組織膠,將其邊緣密合以進行癒合;這被稱為'一般癒合性傷口'。密合之後,傷口通常會覆蓋敷料,來屏障其與外部環境之接觸。敷料的一個可能益處是可以保護傷口免於感染(手術部位感染)。有許多不同類型的敷料可用於手術傷口。然而,尚不清楚在預防手術部位感染方面,是否有某一類型的敷料,比其它任何類型的敷料更為有效,或是在實際上,是否最好完全都不要使用敷料。

研究特點

我們以所有有關敷料在預防手術部位一般癒合性傷口感染上影響可取得的證據,執行此文獻回顧。本篇文獻回顧審查了29個隨機對照試驗(提供最可靠的證據)的數據。這些試驗調查於手術部位感染風險低(清潔手術)和風險較高(可能受污染手術)使用敷料。

主要結果

我們沒有發現任何明確的證據指出,某一種類型的敷料,在降低外科手術部位感染之風險方面,優於其它任何一種,也不能證明使用任一種包覆傷口敷料,皆能降低手術部位感染的風險。另外,沒有明確的證據能表明,任何類型的敷料都能改善疤痕,控制疼痛,提高患者接受度或容易移除。目前,決策者可以根據患者和臨床醫生的偏好和敷料的成本,來決定是否以及如何包覆傷口。

證據確定性

必須要注意的是,本篇文獻回顧中納入的許多試驗規模小,證據確定性低或非常低,意味著目前的資訊是不明確的。

證據更新至2016年9月。

譯註

翻譯者:張頌華
服務單位:自由譯者

本翻譯計畫由臺北醫學大學考科藍臺灣研究中心(Cochrane Taiwan)、台灣實證醫學學會及東亞考科藍聯盟(EACA)統籌執行
聯絡E-mail:cochranetaiwan@tmu.edu.tw

Резюме на простом языке

Повязки для профилактики инфекции области хирургического вмешательства

Вопрос обзора

Целью этого обзора была оценка влияния различных раневых повязок (или же сохранения раны в открытом состоянии, без повязки) на число людей с развившейся после операции раневой инфекцией, в случае закрытия раны швами, скобками, клипсами или клеем. Мы также изучили, приводило ли использование различных повязок к меньшей боли или менее выраженному образованию рубцовой ткани, а также были ли они более приемлемыми для пациентов и специалистов здравоохранения.

Актуальность

Ежегодно в мире проводятся миллионы хирургических вмешательств. Большинство хирургических вмешательств приводят к образованию ран, края которых соединяют с помощью швов, скобок, клипс или клея; это называют "заживлением первичным натяжением". После этого раны часто покрывают повязкой, которая служит барьером между раной и окружающей средой. Одним из возможных преимуществ повязки является защита раны от инфекции (инфекции области хирургического вмешательства). Существует множество разновидностей повязок для хирургических ран. Однако, неясно, насколько одни из них лучше других в профилактике инфекции области хирургического вмешательства, а также не лучше ли не использовать повязки вовсе.

Характеристика исследований

Мы провели обзор всех доступных соответствующих доказательств относительно влияния повязок на профилактику инфекций области хирургического вмешательства в хирургических ранах, заживающих первичным натяжением. В этом обзоре были изучены данные из 29 рандомизированных контролируемых испытаний (представляющих наиболее надежные доказательства). В них оценивали применение повязок при хирургических вмешательствах с низким риском развития инфекции области хирургического вмешательства (чистые операции) и хирургических вмешательствах с более высоким риском (потенциально загрязненные).

Основные результаты

Мы не нашли убедительных доказательств в пользу того, что один тип повязок был лучше других в снижении риска инфекции области хирургического вмешательства, а также что покрытие раны любой повязкой, в целом, снижает риск развития инфекции области хирургического вмештельства. Вдобавок, не было явных доказательств, что какие-либо повязки улучшают процесс рубцевания и контроль боли, а также являются более приемлемыми для пациентов и более легко снимаются. В настоящее время лица, принимающие решения, могут сделать выбор относительного того, использовать ли повязки и какие именно, основываясь на предпочтениях пациентов и клиницистов, а также стоимости повязок.

Уверенность в доказательствах

Важно отметить, что многие испытания в этом обзоре были небольшими, а уверенность в доказательствах была низкой или очень низкой, что означает, что настоящая информация неоднозначна.

Данные актуальны на сентябрь 2016 года.

Заметки по переводу

Перевод: Кукушкин Михаил Евгеньевич. Редактирование: Юдина Екатерина Викторовна. Координация проекта по переводу на русский язык: Cochrane Russia - Кокрейн Россия (филиал Северного Кокрейновского Центра на базе Казанского федерального университета). По вопросам, связанным с этим переводом, пожалуйста, обращайтесь к нам по адресу: cochrane.russia.kpfu@gmail.com; cochranerussia@kpfu.ru

Laički sažetak

Zavoji za sprječavanje infekcije kirurške rane

Istraživačko pitanje

U ovom Cochrane sustavnom pregledu literature je ispitan učinak različitih postupaka zbrinjavanja rane (zavoj ili otvoreno) na infekciju nakon operativnog zahvata i zatvaranja šavima, kvačicama ili ljepilom. Također smo istražili učinak zbrinjavanja rane na bol, ožiljak te prihvatljivost za bolesnike i zdravstvene radnike.

Dosadašnje spoznaje

Broj operativnih zahvata u svijetu je velik. U većine zahvata postoje rane čiji rubovi se zatvaraju šavima, kvačicama ili ljepilom radi cijeljenja, a što se naziva primarnim cijeljenjem (latinski per primam intentionem). Rane se prekrivaju zavojima koji štite od okoliša. Prednost zavoja je u sprječavanju infekcije mjesta operativnog zahvata. Postoje različite vrste zavoja za kirurške rane. Nije poznato postoji li prednost za neku vrstu zavoja u sprječavanju infekcije rane, odnosno važnost primjene zavoja.

Obilježja uključenih istraživanja

Pretražili smo relevantnu literaturu o učinku zavoja na sprječavanje infekcije kirurške rane kod primarnog cijeljenja. Nađeno je 29 randomiziranih kliničkih ispitivanja. Istražen je ishod zavoja kirurških rana s niskim rizikom infekcije rane i visokim rizikom infekcije (potencijalno zagađena rana).

Ključni rezultati

Nisu nađeni dokazi o prednosti vrste zavoja na smanjenje rizika infekcije kirurške rane, te učinak zavoja ili otvorene rane na rizik infekcije. Nije bilo dokaza o učinku vrste zavoja na ožiljavanje, bol, prihvatljivosti za bolesnika ili jednostavnost skidanja zavoja. Odluka i dalje ostaje na bolesniku i kliničaru o načinu zbrinjavanja kirurške rane.

Kvaliteta dokaza

U mnogim studijama je bilo malo ispitanika i dokazi su niske ili vrlo niske kvalitete te je značenje nepouzdano.

Ovaj Cochrane sustavni pregled prikazuje dokaze koji su bili dostupni do rujna 2016.

Bilješke prijevoda

Hrvatski Cochrane
Prevela: Vesna Kušec
 Ovaj sažetak preveden je u okviru volonterskog projekta prevođenja Cochrane sažetaka. Uključite se u projekt i pomozite nam u prevođenju brojnih preostalih Cochrane sažetaka koji su još uvijek dostupni samo na engleskom jeziku. Kontakt: cochrane_croatia@mefst.hr

Streszczenie prostym językiem

Opatrunki w zapobieganiu zakażeniom rany pooperacyjnej

Pytanie przeglądu

Celem tego przeglądu jest sprawdzenie, czy stosowanie różnych rodzajów opatrunków (lub też pozostawienie rany bez opatrunku) ma wpływ na liczbę osób, których rana ulega zakażeniu po operacji, podczas której do zamknięcia rany użyto szwów, szwów mechanicznych (staplera), klipsów lub kleju. Badaliśmy również czy któreś opatrunki zmniejszały ból i wielkość blizny oraz czy były bardziej niż inne akceptowane przez pacjentów i pracowników medycznych.

Wprowadzenie

Każdego roku na świecie przeprowadza się miliony operacji. Większość zabiegów wiąże się z powstaniem ran. Aby się zagoiły, ich brzegi zbliża się do siebie za pomocą szwów, zszywek, klipsów albo kleju. Nazywa się to gojeniem przez pierwotne zamknięcie rany (rychłozrost). Następnie rany pooperacyjne często pokrywa się opatrunkiem, który je oddziela od środowiska zewnętrznego. Zaletą opatrunków może być ochrona rany przed zakażeniami. W użyciu jest wiele rodzajów opatrunków do ran pooperacyjnych. Nie jest jednak jasne, czy któryś opatrunek lepiej zapobiega zakażeniu rany niż inne, albo czy może lepiej nie stosować żadnego opatrunku.

Charakterystyka badania

Dokonaliśmy przeglądu wszystkich dostępnych badań oceniających wpływ opatrunku na ochronę przed zakażeniem rany pooperacyjnej gojącej się przez rychłozrost. Do przeglądu włączyliśmy dane z 29 badań z randomizacją (takie badania dostarczają najbardziej wiarygodnych danych). Analizowano w nich stosowanie opatrunków po operacjach związanych z małym ryzykiem (tzw. rany czyste) i z większym ryzykiem zakażenia rany (rany potencjalnie zanieczyszczone).

Główne wyniki

Nie znaleźliśmy bezspornych dowodów na to, że jakiś rodzaj opatrunku bardziej od innych zmniejsza ryzyko infekcji rany pooperacyjnej, ani też że w ogóle pokrywanie rany jakimkolwiek opatrunkiem zmniejsza ryzyko infekcji. Nie ma też pewnych danych, że jakikolwiek rodzaj opatrunku zmniejsza bliznowacenie i ból albo jest lepiej akceptowany przez pacjentów lub łatwiejszy w usuwaniu. Decyzje o założeniu oraz rodzaju opatrunku powinno się więc obecnie podejmować na podstawie preferencji pacjenta, lekarza oraz kosztów.

Wiarygodność danych

Trzeba zaznaczyć, że wiele badań włączonych do przeglądu było małymi badaniami, a jakość danych naukowych była niska lub bardzo niska; dlatego aktualna wiedza nie jest pewna.

Dane aktualne na wrzesień 2016 r.

Uwagi do tłumaczenia

Tłumaczenie: Mateusz Kaczmarczyk, Redakcja: Łukasz Strzeszyński

எளியமொழிச் சுருக்கம்

நோய்த்தொற்றை தடுக்க அறுவை சிகிச்சை செய்த பகுதிகளில் ஏற்படும் புண்களை கட்டுதல்.

விமர்சன கேள்வி

இந்த ஆய்வின் நோக்கம் பல விதமான காயங்களை கட்டுதலின் பயன்கள் (அல்லது காயங்களை கட்டாமல் விட்டுவிடுதல்) ஆகியவை நோய்த்தொற்றை அறுவை சிகிச்சைக்கு பின் புண்களை தையல்கள் மூலமாகவும்,ஸ்டேபிள்ஸ்,கிளிப்கள் மற்றும் பசைகள் மூலமாகவும், மூடிய புண்களின் மீது நோய் தொற்றை பெற்றவர்கள் மீதான தாக்கத்தை கண்டறிதலாகும். மேலும் நாம் பலவகையிலான காயங்களைக் கட்டுதலின் மூலம் குறைவான வலி, குறைவான தழும்புகள் ஆகிவற்றைக் இதை ஏற்றுக் கொண்ட நோயாளிகள் மற்றும் தொழில் முறை சுகாதார நிபுணர்களை வைத்து ஆய்வை மேற்கொண்டோம்.

பின்னணி

பல இலட்சக்கணக்கான அறுவைசிகிச்சை செயல்முறைகள் பல உலகளவில் ஒவ்வொரு ஆண்டும் நடத்தப்படுகின்றன. பெரும்பாலான புண்கள் அவற்றின் விளிம்புகளை ஒன்றிணைத்து தையல்கள்,ஸ்டேபிள்ஸ்,கிளிப்ஸ், அல்லது பசை பயன்படுத்தி ஒட்டுதல் முறையில் குணப்படுத்தப்படுகின்றது.இது 'முதன்மையாக குணப்படுத்தும் முறை' என்று அழைக்கப்படுகிறது. பிறகு அடிக்கடி காயங்களைக் கட்டுதல் மூலம் உள்ளேயும் வெளியேயும் உள்ள சூழ்நிலைகளுக்கு ஒரு தடையாக மூடப்படுகிறது. மிகவும் சாத்தியமான நன்மை என்னவென்றால் புண்களை நோய் தொற்றிலிருந்து காக்கிறது( அறுவை சிகிச்சை செய்யப்பட்ட இடம்). பல விதமான அறுவை சிகிச்சை செய்த புண்களை கட்டும்முறை உள்ளது. எனினும் அறுவை சிகிச்சை செய்த இடத்தில் நோய் தொற்றை தடுக்கும் ஒருவிதமான கட்டும்முறை மற்ற விதமான கட்டும்முறையை விட சிறந்தது என்று தெளிவாக கூற முடியவில்லை அல்லது உண்மையில் புண்களை கட்டும்முறையை பயன்படுத்தாமல் இருப்பது சிறந்ததோ என்று அறிய இயலவில்லை.

ஆய்வு பண்புகள்

எங்களுக்கு கிடைத்த எல்லா ஆய்வுகளின் தரத்தின் சான்றுகளை வைத்து அறுவைசிகிச்சை பகுதியில் நோய்த்தொற்றுகளினால் ஏற்படும் புண்களை கட்டுவதன் மூலமாக குணமடைதல் பற்றி கண்டறிவதே முதன்மையான எண்ணமாகும். 29 சீரற்ற கட்டுப்பாடு சோதனைகளில் (இது மிகவும் நம்பகமான சான்றுகளை வழங்கும்)இருந்து திறனாய்வு செய்து எடுக்கப்பட்டதகவல்கள். குறைவான ஆபத்துள்ள அறுவைசிகிச்சைப் பகுதிகளில் ஏற்படும் நோய்த்தொற்று (தூய்மையான அறுவைசிகிச்சை) மற்றும் அறுவைசிகிச்சை அதிக ஆபத்துள்ள( அசுத்தமாக சாத்தியமுள்ள) புண்களை கட்டுவதன் பயன்களை கண்டறிந்தோம்.

முக்கிய முடிவுகள்

அறுவை சிகிச்சை செய்த இடத்தில் ஏற்படும் நோய் தொற்றை குறைப்பதில் ஒரு விதமான காயங்களைக் கட்டும்முறை சிறந்தது அல்லது புண்களை மூடும் முறை குறைவான அளவில் நோய் தொற்று ஆபத்தை குறைக்கும் என்று தெளிவாக கூற இயலவில்லை என்று நாம் தெளிவான ஆதாரங்கள் மூலம் கண்டறிந்தோம். கூடுதலாக எந்த விதமான காயங்களை கட்டும் முறை தழும்புகள் குணமடைவதில் முன்னேற்றமும்,வலியை கட்டுக்குள் வைத்திருப்பது,நோயாளியின் ஏற்றுக்கொள்ளும்தன்மை அல்லது கட்டுகளை பிரிக்க எளிதாக இருப்பது குறித்து தெளிவான ஆதாரங்கள் இல்லை. தற்போது எப்படி புண்களை கட்டலாம் என்பதை நோயாளி மற்றும் மருந்தாளர் விருப்பம் மற்றும் கட்டுகளின் விலை ஆகிவற்றைக் கொண்டு முடிவுகளை எடுப்பவர்கள் தீர்மானிக்கலாம்.

ஆதாரங்களின் நிச்சயம்

முக்கியமாக குறிக்கப்படவேண்டியது இந்த திறனாய்வில் பல மிகச் சிறிய ஆய்வுகள் என்பதையும், நம்பகத் தன்மை மிகவும் குறைந்து மற்றும் குறைவான அல்லது மிகவும் குறைவான நிச்சயமற்ற தன்மை என்பதின் அர்த்தம் தற்போதைய தகவல்கள் நம்பகமற்றது என்பதாகும்.

செப்டம்பர் 2016 வரை மதிப்பீடு செய்யப்பட்டது.

மொழிபெயர்ப்பு குறிப்புகள்

மொழிபெயர்ப்பு: தெற்காசிய காக்ரேன் குழு [சங்கீதா, ஜாபெஸ் பால்]

Summary of findings(Explanation)

Summary of findings for the main comparison. Basic wound contact dressing compared with exposed wound
  1. 1 The study had a small sample size and low number of events: the OIS was not met. 95% CIs were wide ranging from a 96% reduced risk of SSI in the exposed group to a 246% increase risk. Downgraded twice for imprecision.

    2 Risk of bias as unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

    3 Study classed as being at high risk of bias for one domain. Downgraded once for study limitations.

    4 The study had a small sample size and low number of events: OIS was not met. 95% CIs were wide ranging from a 18% reduced risk of SSI in the exposed group to a 119% increase risk. Downgraded twice for imprecision.

    5 No data were available to asses this outcome - downgraded twice for imprecision as un/certainty of estimates could not be assessed.

    6 Risk of bias unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

Basic wound contact dressing compared with exposed wound
Patient or population: surgical wounds healing by primary intention
Setting: postsurgical
Intervention: exposed wounds
Comparison: basic wound contact dressing
OutcomesAnticipated absolute effects (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contact dressingRisk with exposed wound

SSI
Assessment method: clinical features of infection

Follow-up: 20 days (for other surgery, not reported for clean surgery)

CLEAN SURGERY
51 per 1000

19 per 1000

(2 to 176)

RR 0.37

(0.04 to 3.46)

112

(1 RCT)

⊕⊝⊝⊝
VERY LOW 1, 2
It is uncertain whether leaving wounds exposed following clean surgery increases or reduces the risk of SSI compared with use of a basic wound contact dressing, as the certainty of the evidence has been assessed as very low.
Risk difference: 32 fewer SSIs per 1000 with exposed wounds (49 fewer to 125 more)
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
206 per 1000

276 per 1000

(173 to 451)

RR 1.34

(0.82 TO 2.19)

207

(1 RCT)

⊕⊝⊝⊝
VERY LOW 3 4
It is uncertain whether leaving wounds exposed reduces or increases the risk of SSI compared with use of a basic wound contact dressing following potentially contaminated surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 70 more SSIs per 1000 with exposed wounds (33 fewer to 245 more)

Scarring

(further information not reported)

CLEAN SURGERY
Not estimableNot estimableOne study reported that there was no difference in quality of final scar between the exposed group and the basic wound contact-dressed group, but no data were presented, nor was any information provided regarding who measured this outcome, how it was measured, or how long after surgery.

112

(1 RCT)

⊕⊝⊝⊝
VERY LOW 5, 6
It is uncertain whether there is any difference in scarring after leaving wounds exposed compared with use of basic wound contact dressings, as the certainty of the evidence has been assessed as very low.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

Acceptability of dressing to participant

Clean surgery

Assessment method:

VAS

Follow-up: not reported

Unclear for other surgery

CLEAN SURGERY
Not estimableNot estimableOne study reported no difference in dressing preference as measured on a linear analogue scale. No further information or data were presented.

112

(1 RCT)

⊕⊝⊝⊝
VERY LOW 5 6
It is uncertain whether leaving wounds exposed following clean surgery is more or less acceptable to patients compared with use of a basic wound contact dressings, as the certainty of the evidence has been assessed as very low.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Ease of dressing removal CLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group (exposed wounds) and the relative effect of the intervention (and its 95% CI).

CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection; VAS: visual analogue scale

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 2 Film dressing compared with exposed wound

Summary of findings 2. Film dressing compared with exposed wound
  1. 1 The study in this comparison was underpowered with a small sample size and a low number of events: the OIS was not met. 95% CIs were very wide ranging from a 98% reduction in SSI risk to a 69% increased risk for exposed wounds. Downgraded twice for imprecision.

    2 Risk of bias as unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

    3 No data were available to asses this outcome - downgraded twice for imprecision as un/certainty of estimates could not be assessed.

Film dressing compared with exposed wound

Patient or population: surgical wounds resulting from clean surgery and healing by primary intention
Setting: postsurgical
Intervention: exposed wounds

Comparison: film dressing

OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with film dressingRisk with exposed wound

SSI
Assessment method: undefined method

Follow-up: mean 20 days

93 per 1000

19 per 1000

(2 to 156)

RR 0.20

(0.02 to 1.69)

107

(1 RCT)

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain whether leaving wounds exposed following clean surgery leads an increase or decrease in risk of SSI compared with use of a film dressing, as the certainty of the evidence has been assessed as very low.
Risk difference: 74 fewer SSIs per 1000 with exposed wounds (91 fewer to 64 more)

Scarring

(further information not reported)

Not estimableNot estimableOne study reported that there was no difference in quality of final scar between the exposed group and the dressed group, but no data were presented, nor was any information provided regarding who measured this outcome, how it was measured, or how long after surgery.

107

(1 RCT)

⊕⊝⊝⊝
VERY LOW 2 3
It is uncertain whether there is any difference in scarring after wound exposure compared with use of film dressings following clean surgery, as the certainty of the evidence has been assessed as very low.

Acceptability of dressing to participant

assessed with: VAS

Follow-up: not reported

Not estimableNot estimableOne study reported no difference in dressing preference as measured on a linear VAS. No further information or data were presented.

107

(1 RCT)

⊕⊝⊝⊝
VERY LOW 2 3
It is uncertain whether leaving wounds exposed is more or less acceptable to patients compared with use of a film dressing following clean surgery, as the certainty of the evidence has been assessed as very low
Ease of dressing removalNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group (exposed wounds) and the relative effect of the intervention (and its 95% CI).

CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection; VAS: visual analogue scale

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 3 Silver dressing compared with exposed wound

Summary of findings 3. Silver dressing compared with exposed wound
  1. 1 The study in this comparison was underpowered with a small sample size and a low number of events: the OIS was not met. 95% CIs were very wide ranging from a 2% increase in SSI risk to a 525% increased risk for exposed wounds. Downgraded twice for imprecision.

    2 Risk of bias as unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

Silver dressing compared with exposed wound

Patient or population: surgical wounds resulting from surgery at risk of contamination and healing by primary intention
Setting: postsurgical
Intervention: exposed wounds

Comparison: silver dressing

OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with silver dressingRisk with exposed wound

SSI
Assessment method: CDC definition of SSI

Follow-up: mean 30 days

96 per 1000

771 per 1000

(98 to 1000)

RR 8.00 (1.02 to 62.55)

166

(1 RCT)

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain whether leaving wounds exposed following surgery at risk of contamination leads to an increase or decrease in risk of SSI compared with use of a silver dressing, as the certainty of the evidence has been assessed as very low.
Risk difference: 675 more SSIs per 1000 with exposed wounds (2 more to 1000 more)
ScarringNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
AcceptabilityNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Ease of dressing removalNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group (exposed wounds) and the relative effect of the intervention (and its 95% CI).

CDC: Centers for Disease Control and Prevention; CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio SSI: surgical site infection;

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 4 Basic wound contact dressing compared with film dressing

Summary of findings 4. Basic wound contact dressing compared with film dressing
  1. 1 One study weighted at 38% in the meta-analysis was classed as being at high risk of bias. Downgraded once for study limitations.

    2 The total number of participants included in the analysis and the number of SSI events were low: the OIS was not met. The 95% CI intervals were wide - ranging from a possible reduction in risk of SSI in the film group of 30% to an increase risk of SSI in the film group of 155%. Downgraded twice for imprecision.

    3 Trial data were imprecise with small sample sizes and wide 95% CIs. Downgraded twice for imprecision.

    4 Risk of bias as unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

    5 Study was classed as being at high risk of bias for two domains. Downgraded twice for study limitations.

    6 Study did not take into account potentially clustered nature of data which could lead to an underestimated standard error. Downgraded once for imprecision.

Basic wound contact dressing compared with film dressing

Patient or population: surgical wounds healing by primary intention
Setting: postsurgical

Intervention: film dressing
Comparison: basic wound contact dressing

OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contact dressingRisk with film dressing

SSI
Assessment method: various methods

Follow-up: unclear

CLEAN SURGERY
34 per 100046 per 1000
(24 to 87)
RR 1.34
(0.70 to 2.55)

897
(4 RCTs)*

*One of the four included trials had no SSI outcome events

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain whether film dressings reduce or increase the risk of SSI compared with use of basic wound contact dressings following clean surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 12 more SSIs per 1000 with film dressings (10 fewer to 53 more)
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimable

Two trials reported SSI data. Due to a lack of information about type of surgery, data were not pooled. One study reported 6/50 participants had an SSI in the basic wound contact group compared with 3/50 in the film-dressed group.

One study, where the level of surgical contamination was unclear, reported 26/46 participants with an SSI in the basic wound contact group compared with 14/44 participants in the film-dressed group.

These data were not pooled.

**A third RCT did not collect SSI data.

190

(2 RCTs)**

⊕⊝⊝⊝
VERY LOW 3 4
It is uncertain whether film dressings increase or reduce the risk of SSIs compared with basic wound contact dressings following surgery with potential for contamination, as the certainty of the evidence has been assessed as very low.
Scarring CLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

Acceptability of dressing to participant

Clean surgery

Assessment method:VAS, participants rated dressing acceptability (0 = no trouble and 10 = very troublesome)

Follow-up: (clean surgery) 6-8 days

Follow-up: unclear for other surgery

CLEAN SURGERY
The mean acceptability score was 4.2 scale unitsMean difference: 2.9 scale units lower (3.59 lower to 2.21 lower)n/a

120

(1 RCT)

⊕⊝⊝⊝
VERY LOW 5 6
It is uncertain whether film dressings are more or less acceptable to patients than basic wound contact dressings following clean surgery, as the certainty of the evidence has been assessed as very low.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

Ease of dressing removal

Assessment method: unclear

Follow-up: unclear

CLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
Not estimableNot estimableOne study reported a proportion figure for ease of dressing removal, but provided no information about how these data were obtained or what the figures mean. The data cannot be interpreted and are not presented.n/an/a 
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group (basic wound contact dressing) and the relative effect of the intervention (and its 95% CI).

CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection; VAS: visual analogue scale
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 5 Basic wound contact dressing compared with hydrocolloid dressing

Summary of findings 5. Basic wound contact dressing compared with hydrocolloid dressing
  1. 1 Study at high risk of bias for outcome assessment. Downgraded once for risk of bias for study limitations.

    2 Studies were small with low numbers of SSI events: the OIS was not met. The 95% CIs around the estimate are wide ranging from a 70% reduction in risk of SSI in the hydrocolloid group to a 178% increase. Downgraded twice for imprecision.

    3Two studies (weighted 65% in the meta-analysis) were at high risk of bias. Downgraded twice for risk of bias for study limitations.

    4 Studies were small with low numbers of SSI events: the OIS was not met. 95% CIs that ranged from a 78% reduction in SSI risk in the hydrocolloid group to a 51% increase. Downgraded twice for imprecision.

    5This was a split-site study with half of a wound treated with one dressing and half with the other. The authors assessed scar colour, texture and colour on a 3-point scale; the lack of independence seems to have been considered by authors, but they only present P values (favouring the hydrocolloid dressing). We have not reproduced the analysis, so given the lack of precision data and the small number of wounds in the study, have downgraded twice for imprecision.

    6 Whilst the study resulted in precise estimates, data are available from just one study with a relatively small number of participants. Further data from more participants would add to certainty. Downgraded once for imprecision. Scarring can also be assessed in a number of ways with width being just one measure, use of a validated tool would be a more useful for decision making. Downgraded once for indirectness.

    7The study had 95% CIs that ranged from a 7% increase risk of dissatisfaction in the hydrocolloid group to 105% increase risk, downgraded once for imprecision.

    8 Risk of bias as unclear for sequence generation and allocation concealment. Downgraded once for study limitations.

    9One study was classed at high risk of bias in two domains. Downgraded twice in limitations.

    10 Studies had small sample sizes. Downgraded once for imprecision.

    11Results were inconsistent - the reason for inconsistency is not clear. Downgraded once for inconsistency.

Basic wound contact dressing compared with hydrocolloid dressing

Patient or population: surgical wounds healing by primary intention

Setting: postsurgical
Intervention: hydrocolloid dressing

Comparison: basic wound contact dressing

OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contactRisk with hydrocolloid dressing

SSI
Clean surgery

Assessment method: CDC definition of SSI

Follow-up: mean 28 days

Other surgery

Assessment method: various clinical measures

Follow-up: 83 days but unclear for one of the RCTs

CLEAN SURGERY
25 per 1000

22 per 1000

(7 to 69)**

RR 0.91

(0.30 to 2.78)

510

(1 RCT)**

**One further trial reported no SSI events and was not included in this presentation of data as it was a split-site study. One further RCT did not report SSI data.

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain if hydrocolloid dressings increase or reduce the risk of SSI compared with use of basic wound contact dressings following clean surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 3 fewer SSIs per 1000 with hydrocolloid dressings (17 fewer to 44 more)
OTHER SURGERY (WITH POTENTIAL FOR CONTAMINATION)
80 per 1000

46 per 1000

(18 to 120)

RR 0.57

(0.22 to 1.51)

268

(3 RCTs)

⊕⊝⊝⊝
VERY LOW 3, 4
It is uncertain if hydrocolloid dressings increase or reduce the risk of SSI compared with basic wound contact dressings following potentially contaminated surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 34 fewer SSIs per 1000 with hydrocolloid dressings (62 fewer to 41 more)

Scarring

Clean surgery

Assessment method: participants assessed different aspects of scarring as either: excellent, good or fair

Follow-up: 4 weeks

potentially contaminated surgery

Assessment method:measurement of scar width (mm)

Follow-up: 3 months

CLEAN SURGERY
Not estimableNot estimable

22/28 (79%) participants reporting on the hydrocolloid dressing rated their scar evenness as excellent compared with 14/28 (50%) reporting on the basic wound contact dressing. P value reported by study authors as 0.008.

22/28 (79%) participants reporting on the hydrocolloid dressing rated their scar colour as excellent compared with 13/28 (46%) reporting on the basic wound contact dressing. P value reported by study authors as 0.004.

21/28 (75%) participants reporting on the hydrocolloid dressing rated their scar suppleness as excellent compared with 15/28 (54%) reporting on the basic wound contact dressing. P value reported by study authors as 0.003.

28

(1 RCT)

⊕⊕⊝⊝
LOW 5
Hydrocolloid dressings may lead to some improvement in cosmetic appearance of scars compared with basic wound contact dressings following clean surgery.
Potentially contaminated surgery
The mean scar width was 2.3 mmMean difference 0.1 mm lower (0.91 lower to 0.7 higher)n/a

134

(1 RCT)**

**One other study reported scar width, but reported no standard deviation or related measure.

⊕⊕⊝⊝

LOW 6

Hydrocolloid dressings may lead to little or no improvement in cosmetic appearance of scars compared with basic wound contact dressings.

Acceptability of dressing to participant

Clean surgery

Assessment method: participants rated whether they were dissatisfied with the dressing

Follow-up: 4 weeks

Unclear for other surgery

CLEAN SURGERY
189 per 1000 (dissatisfied)

280 per 1000

(203 to 388)

RR 1.48 (1.07 to 2.05)

510

(1 RCT)

⊕⊕⊝⊝
LOW 7 8
Hydrocolloid dressings may lead to more dressing dissatisfaction compared with basic wound contact dressings following clean surgery.
Risk difference: 91 more dissatisfied per 1000 with hydrocolloid dressings (13 more to 199 more)
POTENTIALLY CONTAMINATED SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

Ease of dressing removal

Clean surgery

Assessment method: questions regarding dressing removal

Follow-up: mean 4 days

No details for potentially contaminated surgery

Unclear for potentially contaminated surgery

CLEAN SURGERY
Not estimableNot estimable

Two studies reported ease of removal. One trial was a split-site study. Data were not pooled because of this and other inconsistencies.

One study reported 5/84 (6%) of respondents classified basic wound contact dressings as difficult to remove, compared with 13/61 (21%) in the hydrocolloid group.

The second study reported at 3 days postoperatively that 22/28 (79%) participants reporting on the hydrocolloid dressing noted that the dressing was easy to remove compared with 18/28 (64%) reporting on the basic wound contact dressing.

173

(2 RCTs)

⊕⊝⊝⊝
VERY LOW 9 10 11
It is uncertain whether there are differences between hydrocolloid dressings and basic wound contact dressings in terms of ease of removal following clean surgery, as the certainty of the evidence has been assessed as very low.
POTENTIALLY CONTAMINATED SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CDC: Centers for Disease Control and Prevention; CI: Confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 6 Basic wound contact dressing compared with fibrous-hydrocolloid dressing

Summary of findings 6. Basic wound contact dressing compared with fibrous-hydrocolloid dressing
  1. 1 Study with outcome data at high risk of bias for outcome assessment was the only study providing data in this analysis. Downgraded once for risk of bias for study limitations

    2 The studies were small and the number of SSI events low: the OIS was not met. The 95% CIs around the estimate are wide ranging from a 50% reduction in risk of SSI in the hydrocolloid group to a 228% increase. Downgraded twice for imprecision.

Basic wound contact dressing compared with fibrous-hydrocolloid dressing
Patient or population: surgical wounds resulting from clean surgery and healing by primary intention
Setting: postsurgical
Intervention: fibrous-hydrocolloid dressing
Comparison: basic wound contact dressing
OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contact dressingRisk with fibrous-hydrocolloid dressing

SSI
Assessment method: signs of infection (redness, tenderness, swelling or exudate)

Follow-up: mean 6 weeks

49 per 100063 per 1000
(25 to 162)
RR 1.29
(0.50 to 3.28)

364
(3 RCTs)*

* only 1 trial had SSI events

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain whether fibrous-hydrocolloid dressings increase or reduce the risk of SSI compared with basic wound contact dressings following clean surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 14 more SSIs per 1000 with fibrous-hydrocolloid dressings (25 fewer to 112 more)
ScarringNot estimableNot estimableAvailable data could not be summarised

80

(1 RCT)

n/aIt is uncertain whether fibrous-hydrocolloid dressings increase or reduce the quality of scarring compared with basic wound contact dressings following clean surgery, as the data available could not be analysed.
Acceptability of dressing to participantNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Ease of dressing removalNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 7 Basic wound contact dressing compared with polyurethane matrix hydrocolloid dressings

Summary of findings 7. Basic wound contact dressing compared with polyurethane matrix hydrocolloid dressings
  1. 1The study was classed being at high risk of bias in two domains. Downgraded twice for study limitations.

    2 The study had a small sample size and very wide 95% CIs. Downgraded twice for imprecision.

Basic wound contact dressing compared with polyurethane matrix hydrocolloid dressing
Patient or population: surgical wounds resulting from clean surgery and healing by primary intention
Setting: postsurgical
Intervention: polyurethane matrix hydrocolloid dressings
Comparison: basic wound contact dressing
Outcomes

Anticipated absolute effects

(95% CI)*

Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contact dressingRisk with polyurethane matrix hydrocolloid dressing
SSINot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison. Secondary outcomes only were assessed.
ScarringNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Acceptability of dressing to participantNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.

Ease of dressing removal

Assessment method: asked whether dressings were difficult to remove (yes)

Follow-up: 5 days

60 per 1000

750 per 1000

(317 to 1000)

RR 12.60

5.32 to 29.85

173 (only reported data for144 here)

(1 RCT)

⊕⊝⊝⊝
VERY LOW1, 2
It is uncertain whether there are differences between matrix-hydrocolloid dressings and basic wound contact dressings in terms of ease of removal, as the certainty of the evidence has been assessed as very low..
Risk difference: 690 more difficult to remove per 1000 with matrix hydrocolloid dressings (261 more to 1000 more)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: confidence interval; n/a: not applicable; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 8 Basic wound contact dressing compared with silver dressing

Summary of findings 8. Basic wound contact dressing compared with silver dressing
  1. 1 The studies were small and number of SSI events low: the OIS was not met. The 95% CIs ranged from a 53% reduction in risk of SSI in the silver-treated group to an increased risk of 162%. Downgraded twice for imprecision.

    2 Risk of bias as unclear for sequence generation and allocation concealment in one study and high risk of bias for blinded outcome assessment in second study. Downgraded once or study limitations.

    3 Two studies which together contributed 53% of weight to the pooled analysis were classed as being at high risk of bias for two domains. Downgraded twice for risk of bias for study limitations.

    4 The OIS was not met. The 95% CIs ranged from a 49% reduction in risk of SSI in the silver treated group to an increased risk of 37%. There number of SSI events was also low. Downgraded twice for imprecision.

Basic wound contact dressing compared with silver dressing

Patient or population: surgical wounds resulting from a range of surgical procedures with some risk of contamination healing by primary intention

Setting: postsurgical
Intervention: silver dressing
Comparison: basic wound contact dressing

OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contactRisk with silver dressing

SSI

potentially contaminated surgery

SSI

Assessment method: various clinical measures

Mean follow-up: 30 days

Clean surgery

Follow-up unclear

CLEAN SURGERY
253 per 1000

357 per 1000

(218 to 588)

RR 1.11 (0.47 to 2.62)

496

(2 RCTs)

⊕⊝⊝⊝
VERY LOW 1 2
It is uncertain whether silver-containing dressings increase or decrease the risk of SSI compared with basic wound contract dressings following clean surgery, as the certainty of the evidence has been assessed as very low.
Risk difference: 104 more SSIs per 1000 with silver dressings (35 fewer to 334 more)
POTENTIALLY CONTAMINATED SURGERY
86 per 100071 per 1000
(44 to 118)
RR 0.83
(0.51 to 1.37)
1353
(5 RCTs)
⊕⊝⊝⊝
VERY LOW 3 4
It is uncertain if silver-containing dressings increase or reduce the risk of SSI compared with basic wound contact dressings, as the certainty of the evidence has been assessed as very low.
Risk difference: 15 fewer SSIs per 1000 with silver dressings (42 fewer to 32 more)
Scarring CLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
POTENTIALLY CONTAMINATED SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Acceptability of dressing to participantCLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
POTENTIALLY CONTAMINATED SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Ease of dressing removal CLEAN SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
POTENTIALLY CONTAMINATED SURGERY
Not estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group (basic wound contact dressing) and the relative effect of the intervention (and its 95% CI).

CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Summary of findings 9 Basic wound contact dressing compared with non-silver antimicrobial dressings

Summary of findings 9. Basic wound contact dressing compared with non-silver antimicrobial dressings
  1. 1 The study was small and number of SSI events low: the OIS was not met. The 95% CIs ranged from a 97% reduction in risk of SSI in the anti-microbial treated group to an increased risk of 77%. Downgraded twice for imprecision.

Basic wound contact dressing compared with non-silver antimicrobial dressing
Patient or population: surgical wounds resulting from clean surgery and healing by primary intention
Setting: postsurgical
Intervention: polyhexametylene biguanide antimicrobial dressings
Comparison: basic wound contact dressings
OutcomesAnticipated absolute effects* (95% CI)Relative effect
(95% CI)
№ of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Risk with basic wound contact dressingRisk with polyhexametylene biguanide anti-microbial dressing

SSI

Assessment method: CDC definition of SSI

Mean follow-up: 30 days

CLEAN SURGERY
50 per 100011 per 1000
(1 to 88)
RR 0.21
(0.03 to 1.77)
197
(1 RCT)
⊕⊕⊝⊝
LOW 1
It is not clear whether polyhexametylene biguanide antimicrobial dressings reduce SSI risk in postsurgical wounds following clean surgery compared with basic wound contact dressings; the 95% CIs include clinical benefit and harms.
Risk difference: 39 fewer SSIs per 1000 with antimicrobial dressings (49 fewer to 38 more)
ScarringNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Acceptability of dressing to participantNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
Ease of dressing removalNot estimableNot estimableNot estimablen/an/aOutcome not measured or reported for this comparison.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CDC: Centers for Disease Control and Prevention; CI: confidence interval; n/a: not applicable; OIS: optimal information size; RCT: randomised controlled trial; RR: risk ratio; SSI: surgical site infection
GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Background

Description of the condition

Millions of surgical procedures are conducted around the world each year. The majority of procedures result in surgical wounds that will heal by primary intention. This is where wound edges are re-approximated using sutures, staples, clips or glue, either alone, or in combination. Following wound closure, surgical wounds commonly leak fluid or blood within the first 24 hours and they are frequently covered with different types of dressing - including glue-as-a-dressing (tissue glue applied over a wound that has already been closed) - to manage the exudate, provide wound protection and prevent possible external contamination that might lead to surgical site infection (SSI) and delayed healing. A study in the USA found that in over 750,000 episodes of surgical hospitalisation, 1% resulted in an SSI (de Lissovoy 2009), and similar estimates have been found in France (Astagneau 2009). However, such values are known to underestimate the levels of SSI by not considering those that develop outside hospitals (Bruce 2001; Gibbons 2011). In the UK it has been estimated that 4% to 5% of patients undergoing a surgical procedure contract an SSI (Health Protection Agency 2002; Smyth 2008), but this percentage varies greatly depending on the circumstances. Whilst various patient factors can predict the likelihood of SSI, the type of surgical procedure performed exerts a major influence on risk. Surgical procedures involving 'clean' body cavities have much lower numbers of infection, around 3% to 5%, compared with procedures involving body cavities with infected, necrotic or dirty tissue, for example, colorectal surgery, which have surgical infection figures of around 10% to 30% (McLaws 2000). A widely used definition that describes the contamination classification of surgical procedures is given below:

Clean: non-infective operative wounds in which no inflammation is encountered, and neither the respiratory, alimentary, genitourinary tract nor the oro-pharyngeal cavity is entered. In addition these cases are elective, primarily closed, and drained with closed drainage system when required.

Clean/contaminated: operative wounds in which the respiratory, alimentary, genital or urinary tract is entered under controlled conditions and without unusual contamination. Specifically, operations involving the biliary tract, appendix, vagina and oropharynx are included in this category, provided no evidence of infection or a major break in sterile technique is encountered.

Contaminated: fresh, accidental wounds, operations with major breaks in sterile technique or gross spillage from the gastrointestinal tract, and incisions in which acute, non-purulent inflammation is encountered.

Dirty: old traumatic wounds with retained devitalised tissue and those that involve existing clinical infection or perforated viscera. This definition suggests that organisms causing postoperative infection were present in the operative field before the operation.

SSIs not only cause considerable patient morbidity, but also increase the consumption of healthcare resources. In the UK, the mean additional cost of treating an infected surgical wound (compared with a non-infected wound) was estimated at GBP 1618 (Plowman 2001), with much of this extra cost attributable to an increased length of hospital stay (mean increase of 6.5 days) (Plowman 2001). In the USA, de Lissovoy 2009 estimated that the extended length of stay and increased treatment costs associated with SSIs over a one-year period led to approximately 1 million additional inpatient-days, costing an additional USD 1.6 billion.

Whilst SSIs can be difficult to define (one review identified 41 different definitions and 13 grading scales of SSI (Bruce 2001)), the Centers for Disease Control and Prevention (CDC) have published the following guidelines defining superficial and deep incisional SSIs (Horan 2008). A superficial SSI is defined as: an infection occurring within 30 days after the operation, that only involves the skin and subcutaneous tissue of the incision, and is associated with at least one of the following:

  • purulent drainage, with or without laboratory confirmation, from the surgical site;

  • organisms isolated from an aseptically-obtained culture of fluid or tissue from the surgical site;

  • at least one of the following signs or symptoms of infection: pain or tenderness, localised swelling, redness or heat, and the superficial incision is deliberately opened by the surgeon and is culture-positive or not cultured (a culture-negative finding does not meet this criterion);

  • diagnosis of SSI by the surgeon or attending physician.

A deep incisional SSI is defined as: infection that occurs within 30 days after the operative procedure if no implant is left in place, or within one year if an implant is left in place, and the infection appears to be related to the operative procedure and involves deep soft tissues (e.g. fascial and muscle layers) of the incision associated with one of the following:

  • purulent drainage from the deep incision, but not from the organ/space component of the surgical site;

  • a deep incision spontaneously dehisces (opens up) or is deliberately opened by the surgeon and is culture-positive or not cultured when the patient has at least one of the following symptoms: fever or localised pain or tenderness;

  • an abscess, or other evidence of infection involving the deep incision is found on direct examination, during re-operation, or by histopathologic or radiologic examination;

  • diagnosis of a deep incisional SSI by a surgeon or attending physician.

Description of the intervention

Dressings are widely used in the care of wounds. Several attributes of an ideal wound dressing have been described (BNF 2016; Goldman 1992; NICE 2008); these include:

  • the ability of the dressing to absorb and contain exudate without leakage or strike-through;

  • lack of particulate contaminants left in the wound by the dressing;

  • thermal insulation;

  • impermeability to water and bacteria;

  • suitability of the dressing for use with different skin closures (sutures, staples);

  • avoidance of wound trauma on dressing removal;

  • frequency with which the dressing needs to be changed;·

  • provision of pain relief;

  • cosmesis and comfort;

  • effect on formation of scar tissue;

  • transparency to aid visualisation of the wound.

Dressing products have evolved considerably in the last few decades, and now fall into broad, widely-recognised categories, namely:

  • basic wound contact dressings such as gauze or cotton absorbents;

  • 'advanced' dressings such as hydrogels, hydrocolloids and films;

  • antimicrobial and other specialist dressings; and, more recently

  • topical skin adhesives, which can be used to cover an already closed wound - 'glue-as-a-dressing'.

Within these groups there are many hundreds of dressing types available. For ease of comparison in this review, dressings have been classified into groups according to the British National Formulary (BNF) (BNF 2016). However, it is important to note that the distributors of dressings may vary from country to country, and that dressing names may also vary. Below we summarise key dressing groups as well as noting wound exposure where no dressing is used to cover a wound.

Wound exposure

In some cases wounds may be left uncovered following surgery. They may have no dressing at all applied or a simple pad placed on the closed wound to absorb leakage which is removed shortly after.

Basic wound contact dressings

Absorbent dressings and surgical absorbents

Absorbent dressings are applied directly to the wound. Surgical absorbents may be used as secondary absorbent layers in the management of heavily-exuding wounds. Examples include Primapore® (Smith & Nephew), Mepore® (Mölnlycke), and absorbent cotton gauze, BP 1988.

Low-adherence dressings and wound contact materials

Low adherence dressings and wound contact materials are usually cotton pads that are placed directly in contact with the wound. They are either non-medicated (e.g. paraffin gauze dressing), or medicated (e.g. containing povidone iodine or chlorhexidine). Examples include paraffin gauze dressing, BP 1993, Xeroform Dressing® - a non-adherent petrolatum blend with 3% bismuth tribromophenate on fine mesh gauze.

Advanced dressings

Vapour-permeable films

Vapour-permeable films are permeable to water vapour and oxygen, but not to water or micro-organisms. They are normally transparent. Examples include OpSite® (Smith & Nephew) and Tegaderm® (3M).

Hydrocolloid dressings

Hydrocolloid dressings are occlusive dressings composed of a hydrocolloid matrix attached to a base (possibly film or foam). Fluid absorbed from the wound causes the hydrocolloid to liquefy. Examples include Comfeel® (Coloplast) and DuoDerm® (ConvaTec, UK).

Fibrous hydrocolloid dressing (hydrofibre, spun hydrocolloid dressings)

Fibrous hydrocolloid dressings are composed of sodium carboxymethylcellulose which forms a gel when it comes into contact with fluid. Examples include Aquacel® (ConvaTec, UK).

Polyurethane matrix hydrocolloid dressing

Polyurethane matrix hydrocolloid dressings consist of two layers - a polyurethane gel matrix and a waterproof polyurethane top-film designed to act as a bacterial barrier. There is only one dressing of this type listed in the BNF: Cutinova® Hydro (Smith & Nephew).

Antimicrobial dressings

Polyhexametylene biguanide (PHMB) dressing

PHMB dressings are impregnated with the antimicrobial agent polyhexanide.

Topical skin adhesives (glue-as-dressing)

Skin tissue adhesives are currently described in the BNF as being indicated for closure of minor skin wounds and for additional suture support. However, they can be used on an already closed wound as a dressing without an additional covering. They act as a barrier, are sterile before application and contain enbucrilate or octyl 2-cyanoacrylate.

How the intervention might work

Current practice for some surgical wounds healing by primary intention involves placement of a dressing over the closed wound before the patient leaves the clean environment of the operating theatre. This practice assumes that the risk of SSIs may be reduced by providing a barrier to environmental contamination. Furthermore, dressings may have additional roles in managing wound exudate, protecting wounds and their staples or sutures, and meeting patients' expectations by 'hiding' the wound, or, alternatively, when transparent dressings are used, facilitating health professionals' observation of the wound. Conversely, in other practices (e.g. paediatric surgery) it is usual not to use a dressing. This practice assumes that the risk of SSIs may be reduced by allowing the wound to dry. When wounds are covered by 'glue-as-a-dressing' it is also assumed that this acts as a barrier that may reduce external infection.

Why it is important to do this review

Surgical wounds healing by primary intention are commonplace within all elective and emergency surgical practice. It is important to assess whether wound dressings have a potential role in reducing the risk of SSI. Such information could inform allocation of resources to appropriate treatments. Currently these decisions are made with limited review data. In the UK, a government-funded guideline reviewed the data from five trials that are relevant to this review, and concluded that existing studies did not show convincing differences in dressing effectiveness in terms of reducing SSI (NICE 2008). Whilst the review methods were robust, the search date was September 2007, and so studies published after this date were not assessed. Recent World Health Organisation guidelines have been published which assess one group of dressings, advanced dressings, compared with standard dressings (Allegranzi 2016).

Objectives

To assess the effects of wound dressings compared with no wound dressings, and the effects of alternative wound dressings, in preventing SSIs in surgical wounds healing by primary intention.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) that compared the immediate postoperative application of wound dressings with no wound dressings, or compared alternative dressings, for surgical wounds expected to heal by primary intention.

Types of participants

Studies involving adults or children (aged two years and over) who had undergone surgical procedures where healing of the surgical wound was planned by primary intention. Wounds of any contamination level (clean, clean/contaminated, contaminated and dirty) were eligible for inclusion. We excluded procedures involving graft sites, and wounds of the mouth and eye. Participants were required to have dressings applied in the operating theatre, immediately after closure of the skin. We excluded studies where participants had infected wounds at the start of the study.

Types of interventions

The primary intervention was wound exposure or application of wound dressings that could be:

  • basic wound contact dressings: classed as surgical and non-surgical absorbent dressings, low-adherence dressings, impregnated/non-impregnated gauze, and adhesive tape;

  • advanced wound dressings such as hydrogels, hydrocolloids and films;

  • antimicrobial and other specialist dressings;

  • tissue adhesive used as a dressing (glue-as-dressing) on an already closed wound.

We included comparisons of a dressing versus no dressing (exposed wound), and versus alternative dressings. We did not consider trials that compared different application durations of the same dressing (timing trials), as these will form a separate review. Nor did we include trials where the application of topical gels or ointments to wounds (in the absence of a dressing comparator) was evaluated, as we viewed these as different interventions. We did not include trials where the application of tissue adhesive was for the purpose of closing the wound only. The only difference between trial groups for included studies was the method of wound coverage used.

Types of outcome measures

Primary outcomes

Occurence of postoperative SSI as defined by the CDC criteria (Horan 2008), or the authors' definition of SSI. We did not differentiate between superficial and deep-incisional infection.

Secondary outcomes
  • Scarring: as reported by the author.

  • Pain: reported using a validated scale or as reported by the author.

  • Acceptability (participant and clinician): as reported by the author.

  • Ease of removal (participant and clinician): as reported by the author.

  • Cost: any measure of cost of treatment, or other aspects of resource use i.e. other equipment.

Search methods for identification of studies

Electronic searches

In September 2016 for our second update of this review we searched the following electronic databases:

  • the Cochrane Wounds Specialised Register (searched 19 September 2016);

  • the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 2016, Issue 8);

  • Ovid MEDLINE (including In-Process & Other Non-Indexed Citations, MEDLINE Daily and Epub Ahead of Print; 1946 to 19 September 2016);

  • Ovid Embase (1974 to 19 September 2016);

  • EBSCO CINAHL Plus (1937 to 19 September 2016).

The search string for CENTRAL can be found in Appendix 1. The search methods used for the original version of this review can be found in Appendix 2.The search strategies for Ovid MEDLINE, Ovid Embase and EBSCO CINAHL can be found in: Appendix 3; Appendix 4; and Appendix 5. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximising version (2008 revision) (Lefebvre 2011). We combined the Embase search with the Ovid EMBASE filter developed by the UK Cochrane Centre (Lefebvre 2011). We combined the CINAHL searches with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN 2015). There were no restrictions with respect to language, date of publication or study setting.

Searching other resources

We searched the bibliographies of all retrieved and relevant publications identified by these strategies for further studies. While handsearches were not performed for this review, they are conducted by Cochrane Wounds in order to inform the CENTRAL database, which we searched. We did not contact manufacturers of dressings regarding studies for inclusion.

We also searched the following clinical trials registries.

Data collection and analysis

Selection of studies

Two review authors independently assessed the studies' titles and abstracts against the review's inclusion criteria. After this initial assessment, we obtained all studies that might meet these criteria in full. Full papers were checked for eligibility by two review authors, with disagreements resolved by discussion and, where required, the input of a third review author. We extracted details of the eligible studies, and summarised them on a data extraction sheet. Two review authors extracted data independently. If data were missing from reports, we made attempts to contact the study authors to obtain the missing information. Studies that were published in duplicate we only included once, but extracted the maximum amount of data from the papers.

Data extraction and management

All data were extracted independently by two review authors. The following data were extracted:

  • country in which the trial was conducted;

  • type of surgery;

  • classification of surgical contamination (see Table 1 for classification guide);

    Table 1. Classification of surgical contamination of included studies
    ClassificationDescriptionStudy classification
    Clean onlyNon-infective operative wounds in which no inflammation is encountered, and neither the respiratory, alimentary, genitourinary tract nor the oro-pharyngeal cavity is entered. In addition these cases are elective, primarily closed, and drained with closed drainage system when required. Burke 2012; Cosker 2005; De Win 1998; Dickinson Jennings 2015; Lawrentschuk 2002; Law 1987; Langlois 2015; Martin-Trapero 2013; Michie 1994; Moshakis 1984; Politano 2011; Ravnskog 2011; Vogt 2007; Wikblad 1995; Wynne 2004
    Clean/contaminated onlyOperative wounds in which the respiratory, alimentary, genital or urinary tract is entered under controlled conditions and without unusual contamination. Specifically, operations involving the biliary tract, appendix, vagina and oropharynx are included in this category, provided no evidence of infection or a major break in sterile technique is encountered.

    Persson 1995; Ruiz-Tovar 2015

    Not reported for Biffi 2012; Kriegar 2011; Siah 2011 but we put them in this class on the basis of details reported.

    Contaminated onlyFresh, accidental wounds, operations with major breaks in sterile technique or gross spillage from the gastrointestinal tract, and incisions in which acute, non-purulent inflammation is encountered. 
    Dirty onlyOld traumatic wounds with retained devitalised tissue and those that involve existing clinical infection or perforated viscera. This definition suggests that organisms causing postoperative infection were present in the operative field before the operation. 
    Mixed 

    Bennett 2013 (clean and possibly clean/contaminated and contaminated)

    Gardezi 1983;(clean, clean/contaminated and possibly contaminated)

    Hewlett 1996; (predominately clean, some clean/contaminated and possibly contaminated)

    Holm 1998; (clean, clean/contaminated and contaminated)

    Ozaki 2015 (25/500 participants were clean-contaminated and the remaining 475 were clean surgery)

    Phan 1993; (clean, clean/contaminated)

    Shinohara 2008; (clean, clean/contaminated and possibly contaminated)

    No classification  Rohde 1979; Prather 2011
  • eligibility criteria;

  • details of the dressing/treatment regimen received by each group, including the duration that the dressing was in situ;

  • primary and secondary outcome(s) (with definitions);

  • outcome data for primary and secondary outcomes (by group);

  • duration of follow-up;

  • number of withdrawals (by group).

Assessment of risk of bias in included studies

Two review authors independently assessed each included study for risk of bias. Assessment was undertaken using the Cochrane `Risk of bias' tool (Higgins 2011). This tool considers six domains: sequence generation, allocation concealment, blinding, incomplete outcome data, freedom from selective reporting, and other issues (i.e. serious baseline imbalance). A `Risk of bias' table was completed for each eligible study; these data were combined into a `Risk of bias' summary figure where we have tabulated judgements for each domain by study.

Measures of treatment effect

We presented results with 95% confidence intervals (CI). We reported estimates for dichotomous outcomes (e.g. infected: yes/no) as risk ratios (RR) (Deeks 2002). We reported continuous data (e.g. pain) as mean differences (MD), and we calculated overall effect sizes (with 95% CI). 

Unit of analysis issues

When we located three-armed trials where only two of the arms were relevant to the review, we did not extract data for the non-relevant arm. When three-armed studies had two arms randomised to receive different brands of the same dressing, we combined these into one group and treated the trial as a two-armed trial. We did not combine arms in three-armed trials when all the arms received different, relevant interventions, in those cases we included all relevant comparisons.

Dealing with missing data

We did not consider the issue of missing data in the protocol for this review. The problem of missing data is common in trials, especially those of poor quality. Excluding participants from the analysis after randomisation, or ignoring participants lost to follow-up can, in effect, undo the process of randomisation, and thus, potentially, introduce bias into the trial. For our primary outcome, SSI, we assumed that where randomised participants were not included in an analysis, they did not have an SSI (that is they were considered in the denominator but not the numerator). Given the relatively small number of SSI events anticipated, this seemed the most appropriate assumption. When a trial did not specify participant group numbers prior to drop out, we presented only complete case data. We present data for all secondary outcomes as complete case analysis.

Assessment of heterogeneity

Our assessment of heterogeneity comprised an initial assessment of clinical and methodological heterogeneity and the appropriateness of combining study results: that is the degree to which the included studies varied in terms of participant, intervention, outcome and characteristics such as length of follow-up. We supplemented this assessment of clinical and methodological heterogeneity with information regarding statistical heterogeneity of the results - assessed using the Chi² test (we considered that a significance level of P < 0.10 indicated statistically significant heterogeneity) in conjunction with the I² measure (Higgins 2003). I² examines the percentage of total variation across RCTs that is due to heterogeneity rather than chance (Higgins 2003). In general I² values of 25%, or less, may mean a low level of heterogeneity (Higgins 2003), and values of 75%, or more, indicate very high heterogeneity (Deeks 2011). We also examined the variability of the point estimates and the overlap of the confidence intervals, when I² values were less than 50%. Where there was evidence of high heterogeneity we explored this further: see Data synthesis.

Assessment of reporting biases

Reporting biases arise when the dissemination of research findings is influenced by the nature and direction of results. Publication bias, an across-study reporting bias, is one of a number of possible causes of 'small study effects', that is, a tendency for estimates of the intervention effect to appear to be more beneficial in smaller RCTs. Funnel plots allow a visual assessment of whether small study effects may be present in a meta-analysis. A funnel plot is a simple scatter plot of the effect estimates from individual RCTs against some measure of trial size or precision (Sterne 2011). If we had meta-analyses that included 10 or more RCTs, we would have presented funnel plots using Cochrane Review Manager 5 software (RevMan 2014). However, we did not have sufficient studies for this.

Data synthesis

We combined details of included studies in a narrative review according to dressing type and stratified by surgical contamination level. We explored both clinical and statistical heterogeneity. Where appropriate, we pooled data using meta-analysis (conducted using RevMan 5), that is, where studies were considered similar in terms of intervention type, duration, and outcomes. We assessed statistical heterogeneity using the Chi² test (we considered that a significance level of P value less than 0.1 indicated heterogeneity), and the I² test (Higgins 2003). In the absence of clinical heterogeneity, and in the presence of statistical heterogeneity (I² over 50%), we used a random-effects model. Where there was no clinical or statistical heterogeneity, we applied a fixed-effect model.

GRADE assessment and 'Summary of findings' tables

We presented the main results of the review in 'Summary of findings’ tables for the following comparisons:

  • basic wound contact dressings compared with exposed wounds;

  • specific advanced dressings compared with exposed wounds;

  • basic wound dressings compared with specific advanced dressings e.g. film, hydrocolloid;

  • basic wound contact dressings compared with antimicrobial dressings.

These tables present key information concerning the certainty of the evidence, the magnitude of the effects of the interventions examined, and the sum of available data for the main outcomes (Schünemann 2011a). The 'Summary of findings’ tables also include an overall grading of the evidence related to each of the main outcomes using the GRADE approach. This defines the certainty of a body of evidence as the extent to which one can be confident that an estimate of effect or association is close to the true quantity of specific interest. The certainty of a body of evidence involves consideration of within-trial risk of bias (methodological quality), directness of evidence, heterogeneity, precision of effect estimates and risk of publication bias (Schünemann 2011b). We present the following outcomes in the 'Summary of findings’ tables:

  • SSI;

  • scarring;

  • acceptability of dressing to patient;

  • ease of dressing removal.

For relevant outcomes reported for comparisons not listed above we have presented GRADE assessments without a 'Summary of findings' table.

In terms of the GRADE assessment, when making decisions for the risk of bias domain we downgraded only when we had classed studies as being at high risk of bias for one or more domains and/or they were classed as being at unclear risk of bias for both domains that contribute to selection bias. In assessing the precision of effect estimates for SSI we followed GRADE guidance (GRADE 2013), and calculated an optimal information size (OIS) using conventional sample size calculation methods. We used the OIS, along with the size of 95% CIs - in terms of whether they spanned estimates of benefit and harm - to assess for downgrading. We calculated the OIS based on GRADE guidance of using a relative risk reduction of between 20% and 30%. The OIS is summarised below but should not be treated as optimal sample sizes for any future research. Within a GRADE assessment the OIS is used to assess the stability of CIs rather than to assess the appropriateness of a sample size to detect a difference.

Our calculation was: reduction in SSI from 14% to 10% (80% power; alpha 5%) = 2070 participants.

We also followed GRADE guidance and downgraded twice for imprecision when there were very few events and CIs around effects included both appreciable benefit and appreciate harm.

Results

Description of studies

See Characteristics of included studies; Characteristics of excluded studies;Characteristics of studies awaiting classification; Characteristics of ongoing studies for full details of studies identified. We are contacting the authors of three studies to clarify their eligibility for the review (Goharshenasan 2016; Siddiqui 2016; Springer 2015). We identified four relevant on-going studies (ISRCTN06792113; NCT02771015; NCT02904200; NCT02619773).

In searching trial registers we also located records for four studies marked as complete, which we could not link to published data on the basis of the information available (see Table 2). We have tried to contact representatives for these trials to locate possible unpublished data: this work is ongoing.

Table 2. Information on studies listed as completed on trial register with unclear publication status
Studies listed as completed with no published record we are aware of Relevant outcomes listed Database Listed contact
Efficacy of wound care and reduction of wound complications by use of AQUACEL® Ag surgical dressingYes

Clinical trials.gov

clinicaltrials.gov/ct2/show/NCT02445300?term=dressing+AND+surgery&rank=8

Feng Chih Kuo

Chang Gung Memorial Hospital

Prospective, randomised, controlled clinical investigation, comparing two postoperative wound dressings used after elective hip and knee replacementYes

Clinical trials.gov

clinicaltrials.gov/ct2/show/NCT02653183?term=dressing+AND+surgery&rank=10

Being conducted in Belgium

Molnlycke Health

Post-op visible wound dressings in treatment of surgical incisionsUnclear

Clinical trials.gov

clinicaltrials.gov/ct2/show/NCT01577225?term=dressing+AND+surgery&rank=11

Being conducted in China

Smith & Nephew Medical (Shanghai) Ltd

Aquacel compared with traditional post surgical wound dressing in vascular surgery patientsUnclear

Clinical trials.gov

clinicaltrials.gov/ct2/show/NCT00428623?term=dressing+AND+surgery&rank=42

Department of Vascular Surgery, Rigshospitalet

Copenhagen, Denmark, 2100

Included studies

A total of 29 RCTs met the inclusion criteria; nine being added in this 2016 update (Biffi 2012; Dickinson Jennings 2015; Kriegar 2011; Langlois 2015; Ozaki 2015; Politano 2011; Prather 2011; Ruiz-Tovar 2015; Siah 2011). There are now 23 two-arm trials and six three-arm trials in the review. Ruiz-Tovar 2015 was a three-arm trial, but only two arms are relevant here and we did not extract data for the non-relevant arm. In one three-arm trial, two of the three arms were randomised to receive different brands of a film dressing (Cosker 2005). For this review, these two film-dressing groups were combined into one group and the trial was treated as a two-arm trial. Likewise, for Dickinson Jennings 2015 we combined two silver dressing arms. We did not combine arms for the remaining three-arm trials, since all groups were deemed to have received different interventions, and so we included all relevant comparisons.

In all trials the surgical procedure took place in a hospital operating theatre.

In total 15 (52%) of the included trials have been published since 2007 (Bennett 2013; Biffi 2012; Burke 2012; Dickinson Jennings 2015; Kriegar 2011; Langlois 2015; Martin-Trapero 2013; Ozaki 2015; Politano 2011; Prather 2011; Ravnskog 2011; Ruiz-Tovar 2015; Shinohara 2008; Siah 2011; Vogt 2007).

The trials took place in several different countries: 17 were conducted in Europe, four in the UK (Cosker 2005; Hewlett 1996; Law 1987; Moshakis 1984), two in Belgium (De Win 1998; Phan 1993); two in Sweden (Persson 1995; Wikblad 1995), two in Denmark (Holm 1998; Vogt 2007), one in Germany (Rohde 1979), one in Ireland (Burke 2012), two in Spain (Martin-Trapero 2013; Ruiz-Tovar 2015), one in France (Langlois 2015), one in Italy (Biffi 2012), and one in Norway (Ravnskog 2011). Two of the remaining trials were conducted in Australia (Lawrentschuk 2002; Wynne 2004), one in Pakistan (Gardezi 1983), seven in the USA (Bennett 2013; Dickinson Jennings 2015; Kriegar 2011; Michie 1994; Ozaki 2015; Politano 2011; Prather 2011), one in Japan (Shinohara 2008), and one in Singapore (Siah 2011). One trial was published in German (Rohde 1979), and one in Spanish (Martin-Trapero 2013), and we acquired translations of these.

The types of surgical procedures undertaken were varied and included cardiac and/or vascular surgery (Shinohara 2008; Vogt 2007; Wikblad 1995; Wynne 2004); caesarean sections (Bennett 2013), abdominal surgery and/or gastrointestinal surgery (Biffi 2012; Holm 1998; Kriegar 2011; Persson 1995; Martin-Trapero 2013; Rohde 1979), or a number of different surgical procedures within the same trial (Burke 2012; Gardezi 1983; Hewlett 1996; Siah 2011). The surgical procedures in each trial were classified as having been clean, clean/contaminated, contaminated or dirty, or a combination of these (see Table 1 for classification). We recorded when the type of surgery performed was unclear (Rohde 1979). Studies also compared a range of different dressing types and regimens as described below and in Table 3.

Table 3. Trial data
  1. n/r = not reported

Study IDGroupsPrimary outcome SSICostScarringPainAcceptabilityEase of removal
Bennett 2013

Group A: standard soft cloth (n = 262)

Group B: silver ion-eluting dressings (n = 262)

Infection

Group A: 19/262

Group B: 25/262

Group A: USD 1.30 per dressing
(USD 306.80 group total),

Group B: USD 46.36 per dressing (USD 11,080.04
group total)

n/rn/rn/rn/r
Biffi 2012

Group A: standard absorbant dressing (n= 59)

Group B: silver hydrofibre dressing (n = 62)

Infection (clinical and microbiological assessment)

Group A: 11/59

Group B: 9/62

n/rn/rn/rn/rn/r
Burke 2012

Group A: absorbent dressing (n = 62: 35 THA and 27 TKA)

Group B: hydrofiber inner layer and hydrocolloid outer layer (Jubilee dressing) (n = 62: 35 THA and 27 TKA).

Infection

Group A: 0/62

Group B: 0/62

Inflammation

Group A: 3/62

Group B: 3/62

Mean no. of dressing change

Group A:

1 = 8/62

2 = 35/62

3+=19/62

Group B:

1 = 38/62

2 = 19/62

3+= 5/62

n/rn/rn/rn/r
Cosker 2005

Group A: standard absorbent dressing (n = 100)

Group B: transparent film dressing and pad (n = 100)

Group C: film dressing (n = 100)

Group A: 5/100
Group B: 5/100
Group C 4/100
n/rn/rn/rn/rn/r
De Win 1998

Group A: absorbent dressing (n = 6)

Group B: transparent film dressing and pad (n = 8)

Group A: 0/6
Group B: 0/8

Mean total cost of dressings

Group A = BEF 11.5

Group B = BEF 14.3

n/rn/rn/rn/r
Dickinson Jennings 2015

Group A: standard sterile dressing (n = 117)

Group B: metallic silver dressing (n = 116)

Group C: ionic silver dressing (n = 118)

Group A: 3/117

Group B: 1/116

Group C: 2/118

n/rn/r

Measured on a 10-point scale with 0 = no pain and 10 = maximum pain):

Group A: 0.98

Group B: 0.67

Group C: 0.75

No other data reported except a P value of 0.265

Pain at dressing removal:

Group A: 2.37

Group B: 1.47

Group C: 2.38

No other data reported except a P value of 0.025

n/r

Measured on a 5-point scale with 1 = very easy and 5 = very difficult. Authors presented data for % classed very easy. Not clear how this was calculated across removals.

% classed very easy

Group A: 0 (0%)

Group B: 71 (70%)

Group C: 50 (51%)

Gardezi 1983

Group A: conventional gauze dressing (n = 50)

Group B: film dressing (n = 50)

Group A: 6/50
Group B: 3/50
n/rn/r

No data about how this was measured.

Group A: 2/50

Group B: 1/50

n/rn/r
Hewlett 1996

Group A: absorbent dressing (n = 39)

Group B: film dressing (n = 37)

n/r

Dressing cost to complete healing (excluding procedure packs)

Group A: GBP 1.60 Group B: GBP 1.46

Cost including procedure packs:

Group A: GBP 4.36

Group B: GBP 2.84

n/rn/rn/rn/r
Holm 1998Group A: absorbent dressing (n = 37)
Group B: hydrocolloid dressing (n = 36)

Group A: 5/22

Group B: 1/28

Group A: 4 wounds required dressing change;

Group B: 5 wounds required dressing change due to leakage or adherence issues.

Mean width (mm)

Group A: 1.78 (range 1–3)

Group B: 2.26 (range 1–5)

Total cosmetic and functional quality of scar (combined from 6 domain scores: elevation of scar, scar down-binding, supposed inconveniences originating from scar, scar width, colour of scar, cosmetic result, not clear what scores refer to. Units unknown). Group A: 21.5

Group B: 22.6

n/rn/rn/r
Kriegar 2011

Group A: gauze (n = 55)

Group B: silver nylon dressing (n = 55)

Group A: 18/55 (14 superficial and 4 deep)

Group B: 7/55 (5 superficial, 2 deep)

n/rn/rn/rn/rn/r
Law 1987Group A: gauze (n = 59)
Group B: film dressing (n = 54)
Group C: exposed wound (n = 53)

Group A: 3/59

Group B: 5/54

Group C: 1/53

Total dressing cost:

Group A: GBP 6.60

Group B: GBP 42.00

Group C: GBP 0.80

n/rn/rn/rn/r
Lawrentschuk 2002Group A: non-adherent absorbable dressing (n = 25)
Group B: paraffin tulle gras (n = 25)

Group A: 3/25

Group B: 0/25

n/rn/rn/rn/rn/r
Langlois 2015

Group A: gauze (n = 40)

Group B: hydrofibre (n = 40)

Group A: 0/40

Group B: 0/40

n/r

Data on the appearance of scar was reported at 6 weeks - blinded assessment

Stoney Brook scale

Medians with standard deviations

Group A: 0 (SD 1.62)

Group B: 1 (SD 1.71)

The authors did not report what the scores on the Stoney Brook scale related too (what was low and what was high). Literature suggests that the total score is derived by adding the scores on the individual items of the scale and ranges from 0 (worst) to 5 (best).

Categorical scale (poor, acceptable or excellent
categories -

Medians with standard deviations

Group A: 0 (SD 0.71)

Group B: 0.5 (SD 0.63)

Also present data using VAS but not clear whether high or low scores were better.

All collected using a scale and analysed by study authors using means:

1 = not satisfied; 2 = fairly satisfied; 3 = satisfied; 4 = highly
satisfied

Medians with standard deviations

Pain reported by participants

Pain during dressing change

Group A: 4 (SD 0.60)

Group B: 4 (SD 0.48)

Pain outside of dressing change

Group A: 3 (SD 0.90)

Group B: 3 (SD 0.97)

Nurse views of participant pain (no further details)

Group A: 4 (SD 0.69)

Group B: 4 (SD 0.66)

n/r

Collected using a scale and analysed by study authors using means.

1 = not satisfied; 2 = fairly satisfied; 3 = satisfied; 4 = highly
satisfied

Medians with standard deviations

Nurse-reported

Group A: 3 (SD 0.59)

Group B: 4 (SD 0.49)

Martin-Trapero 2013

Group A: non-occlusive dressing (gauze) (n = 101)

Group B: 0.2% (PHMB) dressing (n = 96)

Group A: 5/101

Group B: 1/96

n/rn/rn/rn/rn/r
Michie 1994Group A: cotton gauze impregnated with bismuth tribromophenate (n = 28)
Group B: hydrocolloid dressing (n = 28)

Group A: 0/28

Group B: 0/28

n/r

Participant ratings

Evenness

Group A: Excellent = 14

Good = 8

Fair = 0

Group B:

Excellent = 22

Good = 0

Fair = 0

Colour

Group A: Excellent = 13

Good = 9

Fair = 0

Group B:

Excellent = 22

Good = 0

Fair = 0

Suppleness

Group A: Excellent = 15

Good = 6

Fair = 0

Group B:

Excellent = 21

Good = 0

Fair = 0

Investigator-rated

4-point rating scale scores for

3rd and 4th visits:
Scar suppleness
Group A:

None = 1;

Some = 2; Considerable = 13;

Very much = 10;
Group B:

None = 1;

Some = 1; Considerable = 4;

Very much = 20

Scar raised
Group A:

No = 14;

Some = 11; Considerable = 1

Group B:

No = 21;

Some = 5; Considerable = 0.

Final visit scores (approximately 7 months)
Scar suppleness
Group A:

No = 0;

Some = 0; Considerable = 0;

Very much = 19 Group B:

No = 0;

Some = 0; Considerable = 0;

Very much = 19

Scar raised
Group A:

None = 16; Some = 2; Considerable = 0;

Very much = 0Group B:

None = 18; Some = 0; Considerable = 0;

Very much = 0

Data on pigmentation pulling and itching also reported, but not extracted here.

Past 48 h measured on a VAS where 0 = 'no pain' and 10 = 'most pain'):

First visit:

Group A = 0.89 (SD 1.35)

Group B = 0.92 (SD 1.36)

Second visit:

Group A = 0.02 (SD 0.04)

Group B = 0.008 (SD 0.03)

n/r

Participant's perception of pain on removal:1st visit (measured on a VAS, where 0 = 'no pain' and 10 = 'most pain'):

Group A: 0.03 (SD 0.07) Group B: 0.24 (SD 0.79)

2nd visit

Group A: 0.01 (SD 0.03) Group B: 0.42 (SD 0.68)

Clinician's opinion dressing easy to remove?
1st visit:
Yes:

Group A: 18/25

Group B: 22/25

2nd visit Yes:

Group A: 4/9

Group B: 9/9 (24 did not require dressing removal)

Moshakis 1984Group A: dry gauze dressing
Group B: transparent film dressing
n/rn/rn/r

Assessed by participants on a linear scale 1 to 10 where 1 = no discomfort/pain and 10 = extremely uncomfortable/painful):
Group A: mean 5.1, SE (0.36), SD (2.76);

Group B: mean 1.6, SE (0.19), SD (1.48)

NOTE: SD calculated by review author as (SE* sqrtN)

Assessed by participants on a linear scale 1–10 where 1 equated to no trouble at all, and 10 equated to very troublesome):
Group A: mean 4.2, SE (0.32) SD (2.46)

Group B: mean 1.3, SE (0.15), SD (1.17)
Acceptability: nurse assessed on a linear scale as for participants):
Group A: mean 5.42, SE (0.44) Group B: mean 1.2, SE (0.08)

NOTE: SD calculated by review author as (SE* sqrtN)

n/r
Ozaki 2015

Group A: standard gauze

Group B: silver alginate dressing

Group A: 0/250

Group B: 1/250

n/rn/rn/rn/rn/r
Persson 1995Group A: exposed wounds initially covered with an absorbent dressing removed morning after surgery (n = 30)
Group B: occlusive hydrocolloid dressing (n = 31)

Group A: 2/30

Group B: 2/31

 n/r

Estimated from graphical representation of VAS: 0-100 mm, higher score indicating worse pain).

Group A: 40 mm

Group B: 32 mm

From participants' perception, estimated from graphical representation of VAS: 0–100 mm for each domain listed, with a higher score indicating increased anxiety):
Thought about wound?

Group A: 18 mm

Group B: 32 mm

Found it unpleasant to look at?

Group A: 4 mm

Group B: 4 mm

Worried about infection?

Group A: 7 mm

Group B: 10 mm

Worried about rupture?

Group A: 5 mm

Group B: 8 mm.

Hesitated to shower?

Group A: 5

Group B: 3

n/r
Phan 1993Group A: standard gauze dressing (not named) (n = 86)
Group B: surgical wound ointment with pure Vaseline (Qualifar) without gauze dressing (n = 93)

Group A: 21/86

Group B: 29/93

n/rn/rn/rn/rn/r
Politano 2011

Group A: standard dressing

Group B: silver-impregnated dressing

Group A: 25/70

Group B: 19/75

n/rn/rn/rn/rn/r
Prather 2011

Group A: gauze

Group B: silver nylon

n/rn/rn/r

Reported pain data for 7 days post surgery - using a scale measuring from 0-10 - with 0 being no pain and 10 being worst pain.

At baseline the mean pain score in Groups A and B was 5. Paper presented subsequent data for each day until day 7, when the mean pain score was 4 in Group A and 2 in Group B. No standard deviation data were presented and no further analysis is presented here.

n/rn/r
Ravnskog 2011

Group A: alginate dressing (n = 100)

Group B: hydrofibre dressing (n = 100)

n/r

Length of hospital stay (mean days; SD)

Group A: 8.05; (3.2)

Group B: 8.71; (4.1)

n/r

Pain from the dressing during mobilisation (measured with 10-point VAS where 0 = no
problems and 10 = unbearable problems) Mean (SD)

Group A: 0.42 (1.2)

Group B: 0.34 (1.0)

All measured with 10-point VAS where 0 = no
problems and 10 = unbearable problems. Mean (SD)

Itching under the dressing

Group A: 0.87 (1.6)

Group B: 0.87 (1.6)

Burning pain under the dressing

Group A: 0.50 (1.3)

Group B: 0.54 (1.2)

Discomfort caused by use of the dressing

Group A: 0.56 (1.2)

Group B: 0.59 (1.1)

Pain at removal of the dressing (yes)

Group A: 2.1%

Group B: 15%

Pain score at removal (10-point VAS where 0 = no
problems and 10 = unbearable problems). Mean (SD)

Group A: 0.21 (0.5)

Group B: 0.57 (1.3)

Rohde 1979Group A: conventional dressing (n = 46)
Group B: transparent drape (n = 44)

Mild wound infection (reddening around stitches):

Group A: 52%

Group B: 32%
(only % reported in paper, so n values calculated as: Group A: 24/46

Group B:14/44)

Infection (not clear whether systemic infection or other type of wound infection):

Group A: 7%

Group B: 14%
( as above, n values calculated as: Group A: 3/46

Group B: 6/44)

Cost (per participant): Group A: DEM 10.40 allowing for 3 changes after the operation Group B: DEM 3.60

.
n/r

Comfortable

Group A: 78%

Group B: 80%

n/r

Easy to remove

Group A: 89%

Group B: 95%

Ruiz-Tovar 2015

Group A: gauze and plastic adhesive tape - (n = 49)

Group B: silver-containing dressing (no further details) (n = 49)

Group A: 10/49

Group B: 9/49

n/rn/rn/rn/rn/r
Shinohara 2008Group A: conventional gauze (n = 71)
Group B: occlusive hydrocolloid dressing (n = 63)

Group A: 4/71 Group B: 3/63

(note in the paper there is a difference between table data and narrative results - we have taken table data)

Cost (of dressing per participant): Group A: JPY 779.9 Group B: JPY 714.9

Mean width (standard deviation)

Group A: 2.3 (2.4) mm

Group B: 2.2 (2.4) mm.

n/rn/rn/r
Siah 2011

Group A: wound exposure (n = 83)

Group B: ionic silver-containing dressing (n = 83)

Group A: 8/83

Group B: 1/83

n/rn/rn/rn/rn/r
Vogt 2007Group A: absorbent dressing (n = 80)
Group B: hydrofibre/spun hydrocolloid dressing (n = 80)

6 weeks:

Group A: 7/66 (not full denominator of 80 as 14 of those randomised not included);

Group B: 9/70 (not full denominator of 80 as 10 of those randomised not included)

Cost/per participant: Group A: EUR 10-11.8

Group B: EUR 20.3-48.7

n/rn/r

1-4 days after surgery (participant assessment: composite outcome from discomfort at mobilisation, pain at dressing change, and skin problems. All combined onto 3-point scale where good = discomfort at all; moderate = minor problems and poor = severe problems):
Group A: good = 52(denominator unclear)

Group B: good = 59(denominator unclear)

n/r
Wikblad 1995Group A: absorbent dressing (n = 92)
Group B: hydrocolloid dressing (n = 77)
Group C: polyurethane matrix hydrocolloid dressing (n = 81)
11 participants treated with antibiotics postoperatively; 8 of these had infections in the sternum (5 of these were in the absorbent dressing group). Not reported by group.

Days 1-5 per participant:

Group A: USD 0.73

Group B: USD 3.60

Group C: USD 3.34

n/r

At day 5 (rated on 3-point scale, no pain to very painful, numerator/denominator data not provided):
No pain on removal

Group A: 76%

Group B: 61%

Group C: 14%
(Actual values calculated by review authors using the denominator from the ease of removal data, assuming both variables measured at the same time. Group A: 64/84; Group B: 37/61; Group C: 8/60)

n/r

Ease of removal (dressing assessed by clinician as difficult to remove: difficult to remove? Yes
Group A: 5/84

Group B: 13/61 Group C: 45/60

Wynne 2004Group A: dry absorbent dressing (n = 243)
Group B: hydrocolloid dressing (n = 267)
Group C: film dressing (n = 227)

Group A: 6/243

Group B: 6/267

Group C: 9/227

Median cost per participant:

Group A: AUD 0.52

Group B: AUD 3.93

Group C: AUD 1.59.

n/rn/r

Assessed by participants

Dressing awareness

Group A: 49/243

Group B: 77/267

Group C: 80/227

Movement limitation

Group A: 30/243

Group B: 61/267

Group C: 60/227

Dissatisfied

Group A: 46/243

Group B: 75/267

Group C: 80/227.

n/r

Excluded studies

In total, we excluded 99 studies after screening of the full text. There were a number of reasons for exclusions including 21 studies that were not RCTs and nine studies that included wounds healing by secondary intention, i.e. wounds that were left open, or had broken open, and were healing from deep to superficial layers. Full details are given in the Characteristics of excluded studies.

For a summary PRISMA flow chart see Figure 1.

Figure 1.

Study flow diagram.

Risk of bias in included studies

See Figure 2 for the `Risk of bias' summary: we judged 14 trials as being at high risk of bias for one or more domain (Bennett 2013; Cosker 2005; De Win 1998; Dickinson Jennings 2015; Holm 1998; Kriegar 2011; Moshakis 1984; Ozaki 2015; Persson 1995; Phan 1993; Ravnskog 2011; Vogt 2007; Wikblad 1995; Wynne 2004). We deemed one trial to be at low risk of bias (Ruiz-Tovar 2015).

Figure 2.

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Effects of interventions

See: Summary of findings for the main comparison Basic wound contact dressing compared with exposed wound; Summary of findings 2 Film dressing compared with exposed wound; Summary of findings 3 Silver dressing compared with exposed wound; Summary of findings 4 Basic wound contact dressing compared with film dressing; Summary of findings 5 Basic wound contact dressing compared with hydrocolloid dressing; Summary of findings 6 Basic wound contact dressing compared with fibrous-hydrocolloid dressing; Summary of findings 7 Basic wound contact dressing compared with polyurethane matrix hydrocolloid dressings; Summary of findings 8 Basic wound contact dressing compared with silver dressing; Summary of findings 9 Basic wound contact dressing compared with non-silver antimicrobial dressings

A summary of all extracted trial data can be found in Table 3

Wound dressings compared with exposed wounds (no dressing)

Comparison 1: Basic wound contact dressings compared with exposed wound (no dressing) (2 trials; 319 participants)

Two trials, involving a total of 319 participants, compared wound exposure with basic wound contact dressings. Law 1987 conducted a three-arm trial where the surgical procedure had a 'clean' contamination classification (112 participants). The trial compared a basic wound contact dressing (removed after five days and changed if wound was discharging), with exposed wounds. Phan 1993 undertook a surgical procedure with clean and 'clean/contaminated' contamination classification and compared a basic wound contact dressing (changed twice daily) with exposed wounds that were treated with petroleum jelly (Vaseline).

Primary outcome: SSI
Clean surgery

Law 1987: it is uncertain whether there is a difference in SSI risk between basic wound contact-dressed wounds (3/59; 5%) and exposed wounds (1/53; 2%) (RR for developing SSI in the exposed group compared with the basic wound contact = 0.37, 95% CI 0.04 to 3.46; Analysis 1.1;very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings for the main comparison).

Potentially contaminated surgery
Phan 1993: it is uncertain whether there is a difference in SSIs risk between basic wound contact-dressed wounds (21/102; 21%) and exposed wounds (29/105; 28%) (RR for developing an SSI in the exposed group compared with the basic wound contact group = 1.34; 95% CI 0.82 to 2.19; Analysis 1.1;very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings for the main comparison).

Secondary outcomes
Clean surgery: scarring

Law 1987 reported that there was no difference in quality of final scar between the exposed group and the basic wound contact-dressed group, but did not present data or was any information regarding who measured this outcome, how it was measured, or how long after surgery. The effect of these interventions on scarring is uncertain (very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings for the main comparison).

Clean surgery: acceptability

The trial reported no difference in dressing preference as measured on a linear analogue scale, and presented no further information or data. The effect of these interventions on acceptability is uncertain (very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings for the main comparison).

Clean surgery: costs

Law 1987 reported that the mean total dressing costs per participant for the basic wound contact-dressed group were GBP 6.60 compared with GBP 0.80 in the exposed group. No detailed information was presented i.e. the cost of complications, duration of stay in hospital and nurse time. The cost of dressing data alone is of limited value to decision makers.

Potentially contaminated surgery
Phan 1993 did not present data on secondary outcomes.

Summary: Basic wound contact dressings compared with exposed wounds

It is uncertain whether leaving surgical wounds exposed (no dressing) when healing by primary intention increases or decreases SSI risk compared with use of a basic wound contact dressing following clean surgery or surgery with the potential for contamination; we assessed the certainty of the evidence as very low (downgraded once for risk of bias and twice for imprecision, Summary of findings for the main comparison).

The effect of these interventions on scarring and acceptability of dressings to patients is also uncertain as the certainty of evidence has been assessed as very low (downgraded once for risk of bias and twice for imprecision). The use of dressings incurs additional unit costs, but there are no cost-effectiveness data available from these studies to facilitate informed decision making.

Comparison 2: Film dressings compared with exposed wounds (1 trial; 107 participants)

Law 1987 compared an exposed wound with a film-dressed wound in 107 participants in clean surgery.

Primary outcome: SSI
Clean surgery

Law 1987: it is uncertain whether leaving surgical wounds exposed (1/53; 2%) leads to an increase or decrease in SSI risk compared with film-dressed wounds (5/54; 9%) (RR 0.20, 95% CI 0.02 to 1.69; Analysis 2.1 ; very low certainty evidence, downgraded once for risk of bias and twice for imprecision, Summary of findings 2).

Secondary outcomes
Clean surgery: scarring

Law 1987 reported that there was no difference in quality of final scar between the exposed group and the film group, but presented no data or any information regarding who measured this outcome, how it was measured, or how long after surgery. The effect of these interventions on scarring is uncertain (very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings 2).

Clean surgery: acceptability

The trial reported no difference in dressing preference as measured on a linear analogue scale. No further information or data were presented. The effect of these interventions on acceptability is uncertain (very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings 2).

Clean surgery: costs

Law 1987: total mean dressing costs per participant for the film group were GBP 42.00 compared with GBP 0.80 in the exposed group.

Summary: Film dressings compared with exposed wound

It is uncertain whether leaving surgical wounds to heal by primary intention exposed (no dressing) following clean surgery increases or reduces SSI risk compared with use of a film dressing; we assessed the certainty of the evidence as very low (downgraded once for risk of bias and twice for imprecision, Summary of findings 2). One trial reported that film dressings were more costly than leaving wounds exposed, but there are no cost-effectiveness data available from the trial to facilitate informed decision making.

Comparison 3: Silver dressings compared with exposed wounds (1 trial; 166 participants)

Siah 2011 compared a silver dressing with wound exposure in 166 participants undergoing various types of elective colorectal surgery which were classed by review authors as clean/contaminated.

Primary outcome: SSI

Potentially contaminated surgery

Siah 2011: it is unclear whether leaving a surgical wound exposed (8/83; 10%) leads to an increase or a decrease in SSI risk compared with a silver-dressed wound (1/83; 1%). RR: 8.00, 95% 1.02 to 62.55 (Analysis 3.1; very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings 3).

Secondary outcomes

Siah 2011 reported no relevant secondary outcomes.

Summary: Silver dressings compared with exposed wound

It is uncertain whether leaving surgical wounds that are healing by primary intention exposed (no dressing) following surgery at risk of contamination increases or reduces SSI risk compared with use of a silver dressing; we assessed the certainty of the evidence as very low (downgraded once for risk of bias and twice for imprecision, Summary of findings 3).

Dressings compared with other types of dressings

Comparison 4: Comparisons between different basic wound contact dressings (1 trial; 50 participants)

Lawrentschuk 2002 undertook a surgical procedure with a 'clean' contamination classification and compared a paraffin tulle dressing with a non-adherent dressing in 50 participants (25 in each arm). Both dressing types were applied in the same way. In both groups a compressible, combined dressing was placed over the evaluated dressings with an adhesive elastic dressing then placed over these.

Primary outcome: SSI
Clean surgery

Lawrentschuk 2002: There was no clear difference in SSI risk between paraffin tulle-dressing (0/25; 0%) compared with the non-adherent dressings (3/25; 12%: RR 0.14, 95% CI 0.01 to 2.63; Analysis 4.1; low certainty evidence - downgraded twice for imprecision); the 95% CI are wide and include both clinical benefit (in terms of reduced SSI risk) and harm (in terms of increased SSI risk).

Secondary outcomes

Lawrentschuk 2002 reported no relevant secondary outcomes.

Summary: Basic wound contact dressings compared with different basic wound contact dressings

It is not clear whether paraffin tulle dressings reduce the risk of SSI events in surgical wounds healing by primary intention following clean surgery compared with use of a non-adherent dressing; the 95% CI are wide and include both clinical benefit (in terms of reduced SSI risk) and harm (in terms of increased SSI risk) (low certainty evidence; downgraded twice for imprecision).

Comparison 5: Basic wound contact dressings compared with film dressings (8 trials; 1087 participants)

Eight trials compared a basic wound contact dressing with a film dressing. Five of these trials evaluated wounds resulting from 'clean' surgical procedures (Cosker 2005; De Win 1998; Law 1987; Moshakis 1984; Wynne 2004), and three evaluated wounds resulting from surgical procedures with mixed, or unclear, contamination classifications (Gardezi 1983; Hewlett 1996; Rohde 1979). The trials included a variety of basic wound contact dressings including gauze and surgical absorbents. Similarly, whilst the comparators were all film dressings, different brands were evaluated (five trials evaluated Opsite (Smith & Nephew), three Tegaderm (3M Healthcare), and one an unnamed brand (Cosker 2005 evaluated two film dressings).

Primary outcome: SSI
Clean surgery

Using a fixed-effect model we pooled data from the four trials with participants who had 'clean' surgery and that reported SSI data (Cosker 2005; De Win 1998; Law 1987; Wynne 2004) (Analysis 5.1). One further trial, Moshakis 1984 did not report SSI data. Whilst Law 1987 and Wynne 2004 were three-arm trials, this was the only meta-analysis conducted with their data, so the complete groups relevant to this pooling were used. De Win 1998 reported zero SSI events. There is uncertain evidence on the risk of SSI between basic wound contact-dressed wounds and film-dressed wounds (RR 1.34; 95% CI 0.70 to 2.55; Analysis 5.1; very low certainty evidence downgraded once for risk of bias and twice for imprecision, Summary of findings 4).

Potentially contaminated surgery

Gardezi 1983 conducted several surgical procedures that were classified as clean, clean/contaminated and possibly contaminated. There was no clear evidence of a difference in the risk of SSI in the basic wound contact-dressed group (6/50; 12%) compared with the film-dressed group (3/50; 6%) (RR 0.50 95% CI 0.13 to 1.89; Analysis 5.2; very low certainty evidence downgraded once for risk of bias and twice for imprecision; Summary of findings 4).

Hewlett 1996: did not report SSI data.

We could not be sure of the surgical classification of one further trial Rohde 1979. In total, 24/46 (52%) of participants in the basic wound contact dressing group had a mild wound infection compared with 14/44 (32%) in the film-dressed group (RR 0.61; 95% CI 0.36 to 1.02 in favour of the film dressing. Given the difficulty in classifying the type of surgical procedure(s) undertaken in Rohde 1979, we did not pool this trial with Gardezi 1983. Overall it is unclear whether there is a difference in the risk of SSI in surgeries with different levels of potential contamination (very low certainty evidence downgraded once for risk of bias and twice for imprecision; Summary of findings 4).

Secondary outcomes
Clean surgery: pain

Moshakis 1984: reported the levels of pain in each group. This was measured using a patient-assessed linear scale (1 to 10) where 1 corresponded to 'no discomfort' and 10 to 'extremely uncomfortable or painful'. Mean pain levels in the basic wound contact group were 5.1 (SD 2.78) compared with 1.6 (SD 1.48) in the film-dressed group, favouring film dressings: mean difference (MD -3.50; 95% CI -4.29 to -2.71; Analysis 5.3). We deemed this trial to be at high risk of bias for two domains and it did not take into account the cluster nature of data. Evidence is of very low certainty and all analyses in this trial must be interpreted with caution.

Clean surgery: acceptability

Moshakis 1984: participants and treating nurses were asked to rate their acceptability of the dressings, which were measured using a linear scale where 1 corresponded to 'no trouble' and 10 to 'very troublesome'. The mean response of basic wound contact-dressed participants was 4.2 (SD 2.46) and the mean response of the film-dressed group was 1.3 (SD 1.17; (MD -2.90; 95% CI -3.59 to -2.21, favouring the film-dressed group; Analysis 5.4;very low certainty evidence downgraded twice for risk of bias and once for imprecision; Summary of findings 4).

The mean acceptability response of the treating nurse was 5.4 (SD unknown) in the basic wound contact group and 1.2 (SD unknown) in the film group.

Clean surgery: costs

De Win 1998: reported the total mean cost of dressings per participant in Belgian francs (now replaced by the Euro (EUR)): BEL 11.5 in the basic wound contact-dressed group and BEL 14.3 in the film-dressed group. No further economic data were presented in this trial. Law 1987 reported the mean per participant cost of the dressings in each group: GBP 6.60 in the basic wound contact group and GBP 42.00 in the film group.

Potentially contaminated surgery: ease of removal

Rohde 1979: also reported figures for ease of dressing removal, but as there was no information about how these data were obtained or what they meant, we cannot interpret them (Table 3).

Potentially contaminated surgery: pain

Gardezi 1983: reported a measure for pain in each group, no details were provided regarding collection of these data or how they could be interpreted (Table 3).

Potentially contaminated surgery: costs

Hewlett 1996: reported the mean per participant cost of dressings (including and excluding procedure pack) as GBP 1.60 for the basic wound contact-dressed group compared with GBP 1.46 for the film-dressed group or GBP 4.36 compared with GBP 2.84 when procedure packs were included. Rohde 1979 reported the cost per participant in Deutsch marks (now replaced by EUR) as DEM 10.40 in the basic wound contact-dressed group and DEM 3.60 in the film group.

Summary: Basic wound contact dressings compared with film dressings

It is uncertain whether covering surgical wounds that are healing by primary intention with a film dressing increases or decreases the risk of SSI compared with use of a basic wound contact dressing following clean surgery or following surgery with other (or uncertain) contamination levels; we assessed the certainty of the evidence as very low (downgraded once for risk of bias and twice for imprecision, Summary of findings 4).

It is uncertain whether people with wounds treated with film dressings reported better or worse acceptability compared with basic wound contact dressings (very low certainty evidence downgraded twice for risk of bias and once for imprecision; Summary of findings 4). The cost data presented were too limited to allow us to draw any conclusions based on costs versus benefits.

Comparison 6: Basic contract wound dressings compared with hydrocolloid dressings (6 trials; 792 participants)

Six trials investigated the effect of a basic wound contact dressing compared with a hydrocolloid dressing (Holm 1998; Michie 1994; Persson 1995; Shinohara 2008; Wikblad 1995; Wynne 2004). The basic wound contact dressings were predominantly gauze.

Primary outcome: SSI
Clean surgery

Michie 1994: none of the 28 wound halves randomised to the basic wound contact dressing or the hydrocolloid dressing developed an SSI.

Wikblad 1995 presented no clear SSI data. The authors reported that 11 participants were treated with antibiotics postoperatively, and eight of these participants had infections in the sternum (five of these participants were in the basic wound contact dressing group). No further information was provided. We classed this trial as being at a high risk of bias due to a large amount of missing data.

Wynne 2004: it is uncertain whether there is a difference in SSI risk between hydrocolloid-dressed (6/267; 2%) and basic wound contact-dressed wounds (6/243; 3%) (RR 0.91; 95% CI 0.30 to 2.78; Analysis 6.1; very low certainty evidence downgraded once for risk of bias and twice for imprecision; Summary of findings 5).

Potentially contaminated surgery

We pooled data from all trials in this comparison that presented SSI data (Holm 1998; Persson 1995; Shinohara 2008). It is uncertain whether there is a difference in SSI risk between hydrocolloid-dressed and basic wound contact-dressed wounds: (RR 0.57; 95% CI 0.22 to 1.51; I² = 0%; Analysis 6.1; very low certainty evidence downgraded twice for risk of bias and twice for imprecision; Summary of findings 5).

Secondary outcomes
Clean surgery: scarring

Michie 1994: participants were asked to assess different aspects of scarring as either: excellent, good or fair. This was a split-site trial with halves of the same wound randomised to different dressings.

Four weeks postoperatively:

  • 22/28 (79%) of participants reporting on the hydrocolloid dressing rated their scar evenness as excellent compared with 14/28 (50%) reporting on the basic wound contact dressing. P value reported by trial authors as 0.008.

  • 22/28 (79%) of participants reporting on the hydrocolloid dressing rated their scar colour as excellent compared with 13/28 (46%) reporting on the basic wound contact dressing. P value reported by trial authors as 0.004.

  • 21/28 (75%) of participants reporting on the hydrocolloid dressing rated their scar suppleness as excellent compared with 15/28 (54%) reporting on the basic wound contact dressing. P value reported by trial authors as 0.003.

Data for these outcomes were also extracted at a seven-month visit but are not presented here, as there were more missing data at this later time point. Further scarring assessments by investigators are reported in Table 3

Hydrocolloid dressings may lead to some improvement in cosmetic appearance of scars compared with basic wound contact dressings, but these data were low certainty evidence downgraded twice for imprecision (Summary of findings 5).

Clean surgery: pain

Wikblad 1995 reported pain at dressing removal; 76% of participants (raw data calculated by review author as 64/84) in the basic wound contact group reported no pain on removal, compared with 61% (calculated as 37/61) in the hydrocolloid group: RR 0.80; 95% CI 0.63 to 1.01 (Analysis 6.2). However, a large number of participants were missing from this trial, which we classed as being at high risk of bias.

Clean surgery: acceptability

Wynne 2004: in the basic wound contact group 46/243 (19%) of participants reported that they were dissatisfied with the dressing compared with 75/267 (28%) in the hydrocolloid group (RR 1.48; 95% CI 1.07 to 2.05). It is not possible to tell how this dissatisfaction was influenced by the short time for which the basic wound contact dressing was in situ. It was unclear if participants were blinded to treatment. Hydrocolloid dressings may lead to more dressing dissatisfaction compared with basic wound contact dressings, but these data were low certainty evidence, downgraded once risk of bias and once for imprecision, Summary of findings 5).

Clean surgery: ease of removal

Wikblad 1995 reported at five days postoperatively that 5/84 (6%) of respondents (clinicians) classified basic wound contact dressings as difficult to remove, compared with 13/61 (21%) in the hydrocolloid group (RR 3.58, 95% CI 1.35 to 9.51).

Michie 1994 reported at three days postoperatively that 22/28 (79%) participants reported that the hydrocolloid dressing was easy to remove compared with 18/28 (64%) who reported that the basic wound contact dressing was easy to remove. This was a split-site randomised trial.

It is uncertain whether there are differences between hydrocolloid dressings and basic wound contact dressings in terms of ease of removal as the certainty of the evidence has been assessed as very low (downgraded twice for risk of bias, once for imprecision and once for inconsistency; Summary of findings 5).

Clean surgery: costs

Wikblad 1995 reported the mean dressing cost per participant at USD 0.73 in the basic wound contact dressing group, and USD 3.60 in the hydrocolloid group.

Wynne 2004 reported the median cost per participant of the basic wound contact dressing group as AUD 0.52, compared with AUD 3.93 for the hydrocolloid group. Again this value included only the cost of the dressings themselves, and not other important measures of resource-use that should be considered when using cost as a decision tool, i.e. amount of nurse time, and cost of complications.

Potentially contaminated surgery: scarring

Shinohara 2008: The mean scar width for both groups was very similar; 2.3 mm (standard deviation 2.4 mm) in the basic wound contact group compared with 2.2 mm (standard deviation 2.4 mm) in the hydrocolloid group (mean difference -0.10, 95% CI -0.91 to 0.70). We judged the data to provide low certainty evidence, downgraded once for imprecision and once for indirectness (Summary of findings 5).

Holm 1998 also reported the mean width of scars as 2.26 mm (range 1 mm to 5 mm) in the basic wound contact group and 1.78 mm (range 1 mm to 3 mm) in the hydrocolloid group (no standard deviation or related data presented) (Summary of findings 5).

Potentially contaminated surgery: pain

Persson 1995 reported participants' perceived pain associated with the wound, measured on a visual analogue scale (VAS) (0 to 100 mm) where a higher score indicted worse pain. The mean score for the basic wound contact group was 40 mm compared with 32 mm in the hydrocolloid group (no standard deviation data presented). We cannot interpret the data further.

Potentially contaminated surgery: costs

Shinohara 2008: reported the mean cost of dressings per patient in the basic wound contact group (in Japanese Yen) as JPY 780, compared with JPY 715 in the hydrocolloid group.

Summary: Basic wound contact dressings compared with hydrocolloid dressings

It is uncertain whether covering surgical wounds healing by primary intention with a hydrocolloid dressing increases or decreases the risk of SSI compared with a basic wound contact dressing following clean surgery (very low certainty evidence, downgraded for once risk of bias and twice for imprecision) or following surgery with other contamination levels (very low certainty evidence downgraded twice for risk of bias and twice for imprecision) (Summary of findings 5).

There was some low certainty evidence that hydrocolloid dressings may lead to some improvement in cosmetic appearance of scarring following clean surgery and other surgery types. Conversley there was low certainty evidence that hydrocolloid dressings may lead to more dissatisfaction with the dressing than basic wound contact dressings. It is uncertain whether there are differences between the dressings in terms of ease of dressing removal, as we assessed the certainty of the evidence as very low, (Summary of findings 5).

Wikblad 1995 report that a basic wound contact dressing was less painful at removal than a hydrocolloid dressing, but the analysis had a large amount of missing data and we judged it to be at high risk of bias, as well as being imprecise: we assessed the evidence from this trial as being of very low certainty.

Comparison 7: Basic wound contact dressings compared with fibrous-hydrocolloid (hydrofibre) dressings (3 trials; 364 participants)

Two trials compared a basic wound contact dressing with a hydrofibre dressing (Burke 2012; Vogt 2007). Vogt 2007 randomised 160 participants undergoing elective vascular surgery to either an absorbant dressing or a hydrofibre dressing, while Burke 2012 randomised 124 participants undergoing hip or knee replacement to either an absorbent or a Jubilee dressing. The Jubilee dressing was described as having a hydrofibre inner layer and hydrocolloid outer layer. We considered the hydrofibre layer to be the contact dressing. Langlois 2015 randomised 80 participants undergoing hip or knee replacement to receive a gauze dressing or a hydrofibre dressing.

Primary outcome: SSI
Clean surgery

We included all three studies in this analysis (Burke 2012; Langlois 2015; Vogt 2007). For Vogt 2007 we have used the results of an intention-to-treat analysis including withdrawals in the denominator only (did not have an SSI) as our methodology stipulated. We have also presented the raw data reported for reference purposes (Analysis 7.2).

We pooled data from the studies: there was a total of 364 participants, but only one trial had outcome events (Vogt 2007), so the results are driven by this. It is uncertain whether covering surgical wounds that are healing by primary intention with a fibrous hydrocolloid dressing increases or decreases risk of SSI compared with a basic wound dressing following clean surgery, (RR 1.29; 95% CI 0.50 to 3.28; Analysis 7.1; very low certainty evidence downgraded once due to risk of bias and twice due to imprecision; Summary of findings 6).

Secondary outcomes
Clean surgery: scarring

Langlois 2015 measured patient satisfaction with appearance of scar in three ways. One was using a VAS for which it was not clear whether a low or high score was better. We have not reported this here. The trial also reported data on a categorical scale (poor, acceptable or excellent) and results of the Stoney Brook scale (see Table 3 for these data). Data are reported as medians with standard deviations (usually used to summarise mean data). Since data have not been presented using the mean or categories we have not analysed them further.

Clean surgery: pain

Langlois 2015 assessed by patients and nurses using a four-point scale where 1 was `not satisfied'; 2 was `fairly satisfied'; 3 was `satisfied'; and 4 was `highly satisfied' - see Table 3. The data were presented using medians and standard deviations, which means that further analyses within the review are not possible.

Clean surgery: costs

Vogt 2007: while this trial reported the mean cost per participant (which included dressings, nurse time and other equipment, such as gloves), no further information was provided. The per participant cost of the basic wound contact group was reported in Euros as a range spanning EUR 10 to EUR 11.8 compared with EUR 20.3 to EUR 48.7 for the fibrous-hydrocolloid group.

Burke 2012 reported the mean number of dressing changes for each group, with more participants in the hydrofibre group requiring only one dressing change 61% (38/62), and fewer requiring two dressing changes (31%; 19/62), or three or more dressing changes (8%; 5/62) when compared with the absorbent dressing arm where 56% (35/63) of participants required two dressing changes and 31% (19/62) required three or more dressing changes.

Summary: Basic wound contact dressings compared with fibrous-hydrocolloid (hydrofibre) dressings

It is uncertain whether covering surgical wounds that are healing by primary intention with a fibrous hydrocolloid dressing increases or decreases risk of SSI compared with a basic wound dressing following clean surgery; we assessed the certainty of the evidence as very low (downgraded once due to risk of bias and twice due to imprecision; Summary of findings 6). The cost of fibrous-hydrocolloid dressings was higher than the cost of basic wound contact dressings, but they may require changing less often.

Comparison 8: Basic wound contact dressings compared with polyurethane matrix hydrocolloid dressings (1 trial; 144 participants (estimated))

Wikblad 1995 was a three-arm trial, presented in comparison 6. It investigated the effect of a basic wound contact dressing compared with a polyurethane matrix hydrocolloid dressing after heart surgery.

Primary outcome: SSI
Clean surgery

Wikblad 1995 reported no interpretable data for SSI. The authors reported that 11 participants were treated with antibiotics postoperatively, and eight of these had infections in the sternum (of which five were in the basic wound contact dressing group). No further information was provided and the outcome was considered to be unreported (Summary of findings 7).

Secondary outcomes
Clean surgery: ease of removal

Wikblad 1995: at five days postoperatively 5/84 (6%) of respondents (clinicians) reported that the basic wound contact dressings were difficult to remove, compared with 45/60 (75%) in the hydrocolloid group (RR 12.60, 95% CI 5.32 to 29.85 (no analysis presented); very low certainty evidence downgraded twice for risk of bias and once for imprecision; Summary of findings 7).

Clean surgery: pain

Wikblad 1995 reported pain at dressing removal and ease of removal; 76% of participants (calculated by review author as 64/84) in the basic wound contact dressing group reported no pain on removal, compared with only 14% (calculated by review authors as 8/60) in the hydrocolloid group. Fewer participants in the basic wound contact dressing group reported pain on dressing removal than in the matrix hydrocolloid group (RR 0.17; 95% CI 0.09 to 0.34; Analysis 8.1). A large number of participants were missing from this trial, which we classed as being at a high risk of bias.

Clean surgery: costs

Wikblad 1995 reported the mean dressing cost per patient at USD 0.73 for the basic wound contact dressing group and USD 3.34 for the matrix hydrocolloid group.

Summary: Basic wound contact dressings compared with polyurethane matrix hydrocolloid dressings

It is uncertain whether covering surgical wounds that are healing by primary intention with a polyurethane matrix hydrocolloid dressing increases or decreases the risk of SSI compared with a basic wound contact dressing following clean surgery; we assessed the certainty of the evidence as very low. The only trial to contribute data was poorly reported and at high risk of attrition bias with no SSI outcome data that could be used (Summary of findings 7). It was uncertain whether the basic wound contact dressing was easier to remove than the hydrocolloid dressing (very low certainty evidence; Summary of findings 7). The unit cost of the hydrocolloid dressing was higher than that of the basic wound contact dressing.

Comparison 9: Basic wound contact dressings compared with silver dressings (8 trials; 1959 participants)

Eight studies were considered in this comparison. Two studies included participants undergoing clean surgery (Dickinson Jennings 2015; Politano 2011). Politano 2011 randomised 145 participants to either a basic wound contact dressing or a silver-containing dressing. Twenty-five SSIs were reported in the silver dressing group compared with 19 in the standard dressing group. It was not clear from the report whether these events occurred in separate people, but we have assumed this in our treatment of the data here. Dickinson Jennings 2015 was a three-arm trial that compared a basic wound dressing to two types of silver dressing. For the purpose of the review, we pooled the silver dressing arms.

Six studies compared the use of a basic wound dressing with a silver-containing dressing in surgery at risk of contamination. Four studies involved colorectal surgery (Biffi 2012; Kriegar 2011; Prather 2011; Ruiz-Tovar 2015). Bennett 2013 randomised 524 participants who had undergone a caesarean section; these can be clean, clean/contaminated, contaminated or dirty depending on timing of membrane rupture and other operative conditions - data on the contamination level of the operations was not presented and so we classed it as mixed although it is likely that most operations were clean. Ozaki 2015 randomised 500 people undergoing a non-emergency surgical procedure for peripheral vascular disease.

Primary outcome: SSI
Clean surgery

We pooled SSI data from the two clean surgery studies using a random-effects model (I² = 34%; Chi² P value = 0.22). Based on the average effect, it is uncertain whether silver dressings increase or reduce the risk of SSI compared with a basic wound dressing (RR 1.11; 0.47 to 2.62; Analysis 9.1; very low certainty evidence downgraded once for risk of bias and twice for imprecision; Summary of findings 8).

Potentially contaminated surgery

We pooled SSI data from the studies where surgery was at risk of contamination using a random-effects model ( I² = 40%; Chi² P value = 0.15) (Bennett 2013; Biffi 2012; Kriegar 2011; Ozaki 2015; Ruiz-Tovar 2015). Based on the average effect of silver dressings it is uncertain whether use of silver dressings reduces the risk of SSI after potentially contaminated surgery compared with the basic wound contact dressings (RR 0.83; 95% CI 0.51 to 1.37; Analysis 9.1; very low certainty evidence downgraded twice for risk of bias and twice for imprecision; Summary of findings 8).

Secondary outcomes
Clean surgery: pain

Dickinson Jennings 2015 reported pain data for the three trial arms, but no variation data were reported and we have not considered these data further (see Table 3).

Clean surgery: ease of removal

Dickinson Jennings 2015 reported ease of removal data for the two types of silver dressings, but the data were not clear for the comparator group and so are not considered further (see Table 3).

Potentially contaminated surgery: pain

Prather 2011 measured pain using a 0 to 10 scale with 0 being 'no pain' and 10 being 'worst pain'. At baseline the mean pain score in the silver dressing group was 5 and in the gauze group was 5. Subsequent data were presented for each day until day seven when the mean pain score was 4 in the control group and 2 in the silver group. No standard deviation data were presented and no further analysis is presented here.

Potentially contaminated surgery: costs

Bennett 2013 presented the total dressing costs per group. The group total for the basic wound contact group was USD 307 and the total for the silver group was USD 11,080. No standard deviation data were presented and data are not analysed further.

Summary: Basic wound contact dressings compared with silver-containing dressings

It is uncertain whether covering surgical wounds that are healing by primary intention with a silver-containing dressing increases or decreases the risk of SSI compared with a basic wound contact dressing following clean surgery (very low certainty evidence downgraded once for risk of bias and twice for imprecision) or following potentially contaminated surgery (very low certainty evidence downgraded twice for risk of bias and twice for imprecision; Summary of findings 8). Data for secondary outcomes were very limited.

Comparison 10: Basic wound contact dressing compared with non-silver antimicrobial dressings (1 trial; 197 participants)

Martin-Trapero 2013 randomised participants undergoing elective laparoscopic cholecystectomy to a basic wound contact or PHMB antimicrobial dressing.

Primary outcome: SSI
Clean surgery

It is not clear whether there is a difference in SSI risk between the basic wound contact dressing group (5/101; 5%) and the PHMB dressing-treated group (1/96; 1%), as the 95% CIs are wide and include benefits (in terms of reduced SSI risk) and harms (in terms of increased SSI risks) (RR 0.21, 95% CI 0.03 to 1.77; Analysis 10.1; low certainty evidence downgraded twice due to imprecision; Summary of findings 9).

Secondary outcomes

This trial provided no data for our secondary outcomes..

Summary: Basic wound contact dressings compared with non-silver antimicrobial dressings

It is not clear whether PHMB dressings reduce SSI risk in surgical wounds healing by primary intention compared with a basic wound contact dressing following clean surgery; the 95% CIs are wide and include benefits (in terms of reduced SSI risk) and harms (in terms of increased SSI risks) (low certainty evidence downgraded twice due to imprecision; Summary of findings 9).

Comparison 11: Comparisons between advanced dressings (3 trials; 694 participants)

We considered three studies in this comparison (Ravnskog 2011; Wikblad 1995; Wynne 2004). We included two arms of Wynne 2004 (a three-arm trial): one arm received a film dressing (left in situ for five days) and another a hydrocolloid dressing (also left in situ for five days). Ravnskog 2011 compared an alginate dressing with a hydrofibre dressing in 200 participants undergoing hip replacement. The trial reported only pain data that could be included in this review.

Primary outcome: SSI
Clean surgery

Wikblad 1995 presented no clear data for SSIs.

In Wynne 2004 it was uncertain whether use of a film-dressing reduces risk of SSI (9/227; 4%) compared with a hydrocolloid-dressing (6/267; 2%) (RR 0.57; 95% CI 0.20 to 1.57; Analysis 11.1; very low certainty evidence downgraded once due to risk of bias and twice due to imprecision).

Secondary outcomes

Clean surgery: acceptability

Wynne 2004: in the hydrocolloid group 75/267 (28%) of participants reported that they were dissatisfied with the hydrocolloid dressing compared with 80/227 (35%) in the film group (RR 0.80; 95% CI 0.61 to 1.03) (no analysis presented). It was unclear if participants were blinded to treatment.

Clean surgery: ease of removal

In Wikblad 1995 13/61 (21%) respondents (clinicians) in the hydrocolloid group reported that the dressing was not difficult to remove compared with 45/60 (75%) in the matrix hydrocolloid group (RR 3.52, 95% CI 2.13 to 5.82) (no analysis presented). However, a large number of participants were missing from this trial, which was classed as being at high risk of bias and data were imprecise and uncertain (very low certainty evidence).

Clean surgery: pain

Ravnskog 2011 used a VAS scale to measure: pain from the dressing during mobilisation; Itching under the dressing; burning pain under the dressing; discomfort caused by use of the dressing; and pain score at dressing removal. The data from the VAS scale were not clear, so these were not analysed further. Participants were also asked whether they had pain at removal of the dressing. In total 2.1% in the alginate dressing group had experienced pain compared with 15% in the hydrofibre dressing group (numerator and denominator data were not presented in the trial report).

In Wikblad 1995, 14% of participants (calculated by review authors as 8/60) in the hydrocolloid group reported no pain at dressing removal compared with 61% (calculated as 37/61) in the matrix-hydrocolloid group. However, a large number of participants was missing from this trial, which we classed as being at high risk of bias, and the data are imprecise. The effect of these interventions on pain is uncertain (very low certainty evidence).

Clean surgery: costs

Wikblad 1995 reported the mean dressing cost per participant at USD 3.60 for the hydrocolloid dressing group and USD 3.34 for the matrix hydrocolloid group.

Wynne 2004 reported the median cost of the hydrocolloid dressing group in Australian dollars as AUD 3.93, compared with AUD 1.59 for a film dressing. Again this value included only the cost of the dressings themselves, and not other important measures of resource use that should be considered when using cost as a decision tool, i.e. amount of nurse time, and cost of complications.

Summary: Advanced dressings compared with another advanced dressing

It is uncertain whether covering surgical wounds that are healing by primary intention with a hydrocolloid dressing increases or decreases the risk of SSI compared with a film dressing following clean surgery, as we have assessed the certainty of evidence as very low (downgraded once due to risk of bias and twice due to imprecision). The limited data means that there is uncertainty about whether any one advanced dressing confers better acceptability or usage.

Discussion

Summary of main results

The primary aim of this systematic review was to present and appraise all existing evidence regarding the relative effectiveness of various surgical dressings, including not using a dressing, and using glue as a dressing, on the risk of developing surgical site infections (SSIs) in surgical wounds that are healing by primary intention. We found insufficient evidence that covering surgical wounds with any dressing compared with leaving them exposed influences the subsequent risk of SSI. Similarly there was insufficient evidence on which to base solid conclusions regarding whether any single type of dressing reduces risk of SSIs in wounds resulting from surgery. GRADE assessments of the evidence resulted predominantly in judgements of very low certainty. The studies included in the analyses were small and had low numbers of events. This means that the available evidence had low statistical power and that for most comparisons we could not exclude the possibility that there might be differences in effectiveness; currently, there is not enough information of a high enough certainty to be sure. Some studies were at a high risk of bias and were lacking important details in reports about trial populations or how outcomes were defined and when outcome data were collected.

We included a range of contamination levels for the many trials that investigated 'non clean' surgery, and it was not possible to draw conclusions for each.

For secondary outcomes, there is again uncertainty due to the certainty of the evidence being low or very low. The results of Moshakis 1984 suggested that film dressings might be less painful for patients than other basic wound contact dressings. However, we judged this trial to be at high risk of bias due to inadequate allocation concealment, and the absence of evidence that appropriate statistical procedures had been employed to accommodate the inclusion of some participants as their own controls (bilateral excisions). Wikblad 1995 reported that basic wound contact dressings were significantly less painful on removal than hydrocolloid dressings. However, a large amount of data were missing from this analysis, and we deemed it, too, to be at a high risk of bias. A number of trials suggested that advanced dressings were more expensive than basic wound contact dressings. However, all cost evaluations were very limited, and did not capture all relevant resource-use data, or consider the costs versus the benefits of treatments - which is best practice in economic evaluation. In short the economic data included in these studies did not lend themselves to decision making.

Overall completeness and applicability of evidence

There are many different dressing options to use postoperatively on surgical wounds. We identified 29 studies to include in this review, these assessed several dressing types, as well as leaving wounds exposed. There are no studies that evaluated glue-as-dressing. The included studies reported limited outcome data, even for the primary outcome of SSI. Where SSI was reported, the process used to define infection was often not reported, nor was it clear over what follow-up period data collection took place. Outcomes for other important patient outcomes such as scarring were also poorly reported, with a range of measures used for assessment, which were sometimes unclear. Frequently, studies were very small in terms of number of participants and outcome events, which meant most included studies were very underpowered. Paradoxically the small, underpowered nature of studies means, that as well as being at risk of type 2 errors (that is missing important differences), they are at increased risk of type I errors as statistically significant findings are more likely to be spurious (Button 2010). Overall, the limited methodological reporting, the small sample sizes and the limited quality of outcome data collection, results in an insufficient volume of potentially biased evidence, which may be selectively reported.

Quality of the evidence

In general, the quality of the studies was very low and difficult to assess due to the lack of methodological detail reported. The majority of the included studies were more than 10 years old and did not follow current trial conduct and reporting guidelines, i.e. CONSORT (Schulz 2010). Key areas of good practice include the robust generation of a randomisation sequence (e.g. by a computer-generated randomisation schedule); robust allocation concealment (e.g. through the use of a telephone randomisation service); and blinded outcome assessment where this is possible. Blinded outcome assessment is also crucial for assessment of outcomes such as SSI where there may be a subjective element in decision making, as non-blinded assessment can introduce detection/observer bias (Hróbjartsson 2012), however, blinded assessment was not implemented in six studies, and not clearly reported in 20 more.

Key methodological information should be included in the trial report. In terms of analysis, data from all participants should be included in the analysis whenever possible, i.e. an intention-to-treat analysis should be conducted. Steps should be taken during a trial to minimise missing data as far as possible. Where missing data were an issue, imputation methods should be considered and clearly reported when implemented. When studies plan to evaluate more than one wound per person, or use participants as their own controls, or both, they should consult a statistician regarding both the trial design, sample size issues and the more advanced type of analysis that is required and, where possible, robust economic data should be collected. A number of trials included multiple surgical procedures with different levels of potential contamination; since they did not report data for each type separately, this limited the value of the data for analysis.

Potential biases in the review process

We conducted a comprehensive search that included trial registries, and obtained translations as required, so we do not believe that language bias is an issue. We were not able to explore publication bias using the studies we had, so the potential for bias for that is unknown. We did not deviate from the prepublished protocol, so do not believe bias has been introduced in terms of selective outcome reporting on our part.

It is noteworthy that we found four studies reported on a trial register (one of these trials was reported on two registers) which we are unable to link to published data. We contacted trial contacts to try to obtain any data we did not have. Where unpublished data exist and are not included in a review, there is an increase in the risk of publication bias.

Agreements and disagreements with other studies or reviews

We are not aware of any other published systematic reviews of dressings for surgical wounds that are healing by primary intention. Another review, however, regarding the use of wound dressings on surgical wounds was conducted as part of the development of a set of UK clinical guidelines addressing the prevention and treatment of SSIs (NICE 2008). This review generally reached similar conclusions to this systematic review. We would like to note, however, that the conclusions of this Cochrane Review are based on additional trials that were not included in the NICE review.

Our review does differ from the NICE review with regard to our use of healing data from Wikblad 1995. We did not utilise the limited infection data that were provided solely in the text of this three-arm trial (which reported that 11 participants were treated with antibiotics postoperatively; eight had infections in the sternum: five were from the basic wound contact dressing group, but group(s) for the remaining three participants were not specified). The NICE review merged two of the three trial arms (a hydrocolloid-dressed arm and a film-dressed arm), and, as we cannot replicate their analysis, its authors may have obtained additional data (they reported six SSIs in the basic wound contact group and two in the merged hydrocolloid/film group). With regard to this trial, the NICE review concluded that: "there is limited evidence to suggest that there is a difference favouring the use of hydrocolloids or 'hydroactive' (film) dressings against the use of absorbent dressings in the prevention of SSI". Our review does not agree with this finding; however, the overall conclusions of the NICE review regarding wound dressings were limited to: "Cover surgical incisions with an appropriate interactive dressing at the end of the operation". The NICE report also conducted its own costing exercise, given that there were no data from the studies that could be used. They concluded that it is important to take into account the additional costs of changing dressings, as well as the initial price of each dressing type, when choosing dressings to use (NICE 2008).

The recent World Health Organisation guideline is supported by a systematic review containing 19 trials - all included here. The review had a narrower remit comparing advanced dressings with standard dressings. The review reports advanced dressings as: Hydrocolloid; Silver-impregnated Hydroactive and PHMB. The review also reports very low quality evidence for each of these comparisons (Allegranzi 2016). The guideline recommendation, suggests not using advanced dressings in preference to standard dressings on primarily closed surgical wounds for the purpose of preventing SSI and rates the evidence as low quality.

Authors' conclusions

Implications for practice

There is currently insufficient evidence to determine whether covering surgical wounds that are healing by primary intention with wound dressings reduces the risk of surgical site infections (SSIs), or whether any particular type of wound dressing reduces the risk of infections more than another. Our review also failed to demonstrate any clear advantage of one dressing type over another (or wound exposure) for improved scarring, pain control, patient acceptability or ease of removal. It is important to note that many trials in this review were small and of poor quality, and at high or unclear risk of bias. Given the current evidence, decision makers may wish to make wound dressing choices on costs and clinician and patient preference. Additional steps to prevent SSIs can be based on other existing evidence and guidelines, for example the use of hand decontamination and antibiotic prophylaxis (NICE 2008).

Implications for research

There is a lack of high quality research evidence regarding whether choice of wound dressing (or indeed use of wound dressings at all) affects the risk of SSIs in people whose surgical wounds are healing by primary intention. Whilst uncertainty remains regarding the best approach to dressing these surgical wounds, any investment in future research must maximise its value to decision-makers. Given both the large number of dressing options and surgical procedures, the design of future trials should focus on those surgical procedures at highest risk of SSI, as well as evaluating the dressings or approaches that health professionals use most widely. In addition, as SSIs can be relatively rare events, very large trials are needed in terms of participant numbers. Such epidemiological information is vital to inform dressing trials and will become available through robust, routine data collection. Additionally, there may be value in asking decision-makers (including patients) what they feel are the most pressing issues, e.g. type of dressing, or duration that a dressing remains in situ, as well as which outcomes are most important, including the ability of different dressings to manage specific symptoms such as absorption of exudate. Such planning means that research resources can be focused to address priorities. Where trials are conducted, good practice guidelines must be followed in their design, implementation and reporting.

Acknowledgements

The authors would like to acknowledge the contribution of peer referees at both the protocol, review and update stage: Andrea Nelson, Joan Webster, Gill Worthy, Laura Bolton, John McCall, Sonya Osborne, Mark Rogers and Jane Nadel. We would also like to thank Elizabeth Royle for copy editing the review and the updated reviews.

Data and analyses

Download statistical data

Comparison 1. Basic wound contact dressings compared with exposed wounds
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI2 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
1.1 Clean surgery1112Risk Ratio (M-H, Fixed, 95% CI)0.37 [0.04, 3.46]
1.2 Potentially contaminated surgery1207Risk Ratio (M-H, Fixed, 95% CI)1.34 [0.82, 2.19]
Analysis 1.1.

Comparison 1 Basic wound contact dressings compared with exposed wounds, Outcome 1 Proportion of wounds with SSI.

Comparison 2. Film dressings compared with exposed wounds
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 2.1.

Comparison 2 Film dressings compared with exposed wounds, Outcome 1 Proportion of wounds with SSI.

Comparison 3. Silver dressings compared with exposed wounds
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 3.1.

Comparison 3 Silver dressings compared with exposed wounds, Outcome 1 Proportion of wounds with SSI.

Comparison 4. Comparisons between basic wound contact dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 4.1.

Comparison 4 Comparisons between basic wound contact dressings, Outcome 1 Proportion of wounds with SSI.

Comparison 5. Basic wound contact dressings compared with film dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI: clean surgery4897Risk Ratio (M-H, Fixed, 95% CI)1.34 [0.70, 2.55]
2 Proportion of wounds with SSI2 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
3 Pain associated with dressing (patient assessed)1 Mean Difference (IV, Fixed, 95% CI)Subtotals only
4 Patient acceptability1 Mean Difference (IV, Fixed, 95% CI)Subtotals only
Analysis 5.1.

Comparison 5 Basic wound contact dressings compared with film dressings, Outcome 1 Proportion of wounds with SSI: clean surgery.

Analysis 5.2.

Comparison 5 Basic wound contact dressings compared with film dressings, Outcome 2 Proportion of wounds with SSI.

Analysis 5.3.

Comparison 5 Basic wound contact dressings compared with film dressings, Outcome 3 Pain associated with dressing (patient assessed).

Analysis 5.4.

Comparison 5 Basic wound contact dressings compared with film dressings, Outcome 4 Patient acceptability.

Comparison 6. Basic wound contact dressings compared with hydrocolloid dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI5 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
1.1 Clean2566Risk Ratio (M-H, Fixed, 95% CI)0.91 [0.30, 2.78]
1.2 Potentially contaminated surgery3268Risk Ratio (M-H, Fixed, 95% CI)0.57 [0.22, 1.51]
2 No pain on removal1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 6.1.

Comparison 6 Basic wound contact dressings compared with hydrocolloid dressings, Outcome 1 Proportion of wounds with SSI.

Analysis 6.2.

Comparison 6 Basic wound contact dressings compared with hydrocolloid dressings, Outcome 2 No pain on removal.

Comparison 7. Basic wound contact dressings compared with fibrous-hydrocolloid (hydrofibre) dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI3364Risk Ratio (M-H, Fixed, 95% CI)1.29 [0.50, 3.28]
2 Proportion of wounds with SSI - Vogt 2007 raw data1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 7.1.

Comparison 7 Basic wound contact dressings compared with fibrous-hydrocolloid (hydrofibre) dressings, Outcome 1 Proportion of wounds with SSI.

Analysis 7.2.

Comparison 7 Basic wound contact dressings compared with fibrous-hydrocolloid (hydrofibre) dressings, Outcome 2 Proportion of wounds with SSI - Vogt 2007 raw data.

Comparison 8. Basic wound contact dressings compared with matrix hydrocolloid dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 No pain on removal1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 8.1.

Comparison 8 Basic wound contact dressings compared with matrix hydrocolloid dressings, Outcome 1 No pain on removal.

Comparison 9. Basic wound contact dressings compared with silver dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI7 Risk Ratio (M-H, Random, 95% CI)Subtotals only
1.1 Clean2496Risk Ratio (M-H, Random, 95% CI)1.11 [0.47, 2.62]
1.2 Potentially contaminated surgery51353Risk Ratio (M-H, Random, 95% CI)0.83 [0.51, 1.37]
Analysis 9.1.

Comparison 9 Basic wound contact dressings compared with silver dressings, Outcome 1 Proportion of wounds with SSI.

Comparison 10. Basic wound contact dressing and non-silver antimicrobial dressing
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 10.1.

Comparison 10 Basic wound contact dressing and non-silver antimicrobial dressing, Outcome 1 Proportion of wounds with SSI.

Comparison 11. Comparisons between advanced dressings
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Proportion of wounds with SSI1 Risk Ratio (M-H, Fixed, 95% CI)Subtotals only
Analysis 11.1.

Comparison 11 Comparisons between advanced dressings, Outcome 1 Proportion of wounds with SSI.

Appendices

Appendix 1. Search strategy for the Cochrane Central Register of Controlled Trials (CENTRAL)

#1 MeSH descriptor: [Bandages] explode all trees
#2 MeSH descriptor: [Hydrogels] explode all trees
#3 MeSH descriptor: [Alginates] explode all trees
#4 (dressing* or hydrocolloid* or alginate* or hydrogel* or foam or bead or film or films or tulle or gauze or non-adherent or non adherent):ti,ab,kw (Word variations have been searched)
#5 MeSH descriptor: [Tissue Adhesives] explode all trees
#6 MeSH descriptor: [Fibrin Tissue Adhesive] explode all trees
#7 tissue next adhesive*:ti,ab,kw (Word variations have been searched)
#8 MeSH descriptor: [Cyanoacrylates] explode all trees
#9 octylcyanoacrylate*:ti,ab,kw (Word variations have been searched)
#10 Dermabond:ti,ab,kw (Word variations have been searched)
#11 MeSH descriptor: [Enbucrilate] explode all trees
#12 Enbucrilate:ti,ab,kw (Word variations have been searched)
#13 butylcyanoacrylate*:ti,ab,kw (Word variations have been searched)
#14 MeSH descriptor: [Acrylates] explode all trees
#15 acrylate*:ti,ab,kw (Word variations have been searched)
#16 MeSH descriptor: [Bucrylate] explode all trees
#17 bucrylate*:ti,ab,kw (Word variations have been searched)
#18 {or #1-#17}
#19 MeSH descriptor: [Surgical Wound Infection] explode all trees
#20 MeSH descriptor: [Surgical Wound Dehiscence] explode all trees
#21 (surg* near/5 infect*):ti,ab,kw
#22 (surg* near/5 wound*):ti,ab,kw
#23 (wound* near/5 infection*):ti,ab,kw
#24 (surg* near/5 incision*):ti,ab,kw
#25 (surg* near/5 site*):ti,ab,kw
#26 {or #19-#24}
#27 {and #18, #26} in Trials

Appendix 2. Search methods used in the original review

For the original review, we searched the following electronic databases:

  • Cochrane Wounds Specialised Register (searched 10 May 2011);

  • The Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 2011, Issue 2);

  • Ovid MEDLINE (1950 to April Week 4 2011);

  • Ovid MEDLINE (In-Process & Other Non-Indexed Citations, 9 May, 2011);

  • Ovid Embase (1980 to 2011 Week 18);

  • EBSCO CINAHL (1982 to 6 May 2011)

The search used is listed below

#1 MeSH descriptor Bandages explode all trees#2 (dressing* or hydrocolloid* or gauze* or hydrogel* or alginate* or "bead" or "foam"):ti,ab,kw
#3 (#1 OR #2)
#4 MeSH descriptor Surgical Wound Infection explode all trees
#5 MeSH descriptor Surgical Wound Dehiscence explode all trees
#6 (surg* NEAR/5 infect*):ti,ab,kw
#7 (surg* NEAR/5 wound*):ti,ab,kw
#8 (wound* near/5 infection*):ti,ab,kw
#9 (surg* NEAR/5 incision*):ti,ab,kw
#10 (surg* NEAR/5 site*):ti,ab,kw
#11 (#4 OR #5 OR #6 OR #7 OR #8 OR #9)
#12 (#3 AND #11)

The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision) (Lefebvre 2009). The Ovid EMBASE and EBSCO CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2010). There were no restrictions on the basis of date or language of publication.

Appendix 3. Ovid MEDLINE search strategy

1. exp Bandages/

2. exp Hydrogels/

3. exp Alginates/

4. (dressing* or hydrocolloid* or alginate* or hydrogel* or foam or bead or film or films or tulle or gauze or non-adherent or non adherent).ti,ab.

5. exp Tissue Adhesives/

6. exp Fibrin Tissue Adhesive/

7. tissue adhesive$.mp.

8. exp Cyanoacrylates/

9. octylcyanoacrylate$.mp.

10. Dermabond.mp.

11. exp Enbucrilate/

12. Enbucrilate$.mp.

13. butylcyanoacrylate$.mp.

14. exp Acrylates/

15. acrylate$.mp.

16. exp Bucrylate/

17. bucrylate$.mp.

18. or/1-17

19. exp Surgical Wound Infection/

20. exp Surgical Wound Dehiscence/

21. (surg* adj5 infection*).ti,ab.

22. (surg* adj5 wound*).ti,ab.

23. (wound* adj5 infection*).ti,ab.

24. surgical site*.mp.

25. or/19-24

26. randomised controlled trial.pt.

27. controlled clinical trial.pt.

28. randomi?ed.ab.

29. placebo.ab.

30. clinical trials as topic.sh.

31. randomly.ab.

32. trial.ti.

33. or/26-32

34. exp animals/ not humans.sh.

35. 33 not 34

36. and/18,25,35

Appendix 4. Ovid EMBASE search strategy

1. exp Wound Dressing/

2. exp Hydrogel/

3. exp Alginic Acid/

4. (dressing* or hydrocolloid* or alginate* or hydrogel* or foam or bead or film or films or tulle or gauze or non-adherent or non adherent).ti,ab.

5. exp Tissue Adhesive/

6. exp Fibrin Glue/

7. (tissue adj adhesive$).mp.

8. exp Cyanoacrylate Derivative/

9. exp Cyanoacrylic Acid Octyl Ester/

10. octylcyanoacrylate$.mp.

11. Dermabond.mp.

12. exp ENBUCRILATE/

13. enbucrilate.mp.

14. butylcyanoacrylate$.mp.

15. exp Acrylic Acid/

16. acrylate$.mp.

17. exp Bucrilate/

18. bucrylate$.mp.

19. or/1-18

20. exp Surgical Wound Infection/

21. exp Wound Dehiscence/

22. (surg* adj5 infection*).ti,ab.

23. (surg* adj5 wound*).ti,ab.

24. (wound* adj5 infection*).ti,ab.

25. surgical site*.ti,ab.

26. or/20-25

27. Randomized controlled trials/

28. Single-Blind Method/

29. Double-Blind Method/

30. Crossover Procedure/

31. (random$ or factorial$ or crossover$ or cross over$ or cross-over$ or placebo$ or assign$ or allocat$ or volunteer$).ti,ab.

32. (doubl$ adj blind$).ti,ab.

33. (singl$ adj blind$).ti,ab.

34. or/27-33

35. exp animals/ or exp invertebrate/ or animal experiment/ or animal model/ or animal tissue/ or animal cell/ or nonhuman/

36. human/ or human cell/

37. and/35-36

38. 35 not 37

Appendix 5. EBSCO CINAHL search strategy

S34 S13 AND S21 AND S33

S33 S22 or S23 or S24 or S25 or S26 or S27 or S28 or S29 or S30 or S31 or S32

S32 TX allocat* random*

S31 (MH "Quantitative Studies")

S30 (MH "Placebos")

S29 TX placebo*

S28 TX random* allocat*

S27 (MH "Random Assignment")

S26 TX randomi* control* trial*

S25 TX ( (singl* n1 blind*) or (singl* n1 mask*) ) or TX ( (doubl* n1 blind*) or (doubl* n1 mask*) ) or TX ( (tripl* n1 blind*) or (tripl* n1 mask*) ) or TX ( (trebl* n1 blind*) or (trebl* n1 mask*) )

S24 TX clinic* n1 trial*

S23 PT Clinical trial

S22 (MH "Clinical Trials+")

S21 S14 or S15 or S16 or S17 or S18 or S19 or S20

S20 TI (postoperative* N5 infection* OR post-operative* N5 infection*) or AB (postoperative* N5 infection* OR post-operative* N5 infection*)

S19 TI wound* N5 infection* or AB wound* N5 infection*

S18 TI surg* N5 wound* or AB surg* N5 wound*

S17 TI surg* N5 infection* or AB surg* N5 infection*

S16 (MH "Surgical Wound")

S15 (MH "Surgical Wound Dehiscence")

S14 (MH "Surgical Wound Infection")

S13 S1 OR S2 OR S3 OR S4 OR S5 OR S6 OR S7 OR S8 OR S9 OR S10 OR S11 OR S12

S12 TI Dermabond or AB Dermabond

S11 TI enbucrilate or AB enbucrilate

S10 TI bucrylate* or AB bucrylate*

S9 TI acrylate* or AB acrylate*

S8 TI butylcyanoacrylate* or AB butylcyanoacrylate*

S7 TI octylcyanoacrylate* or AB octylcyanoacrylate*

S6 TI cyanoacrylate* or AB cyanoacrylate*

S5 TI tissue adhesive* or AB tissue adhesive*

S4 (MH "Fibrin Tissue Adhesive")

S3 TI ( dressing* or pad or pads or gauze or tulle or film or bead or foam* or non-adherent or non adherent or hydrocolloid* or alginat* or hydrogel* ) or AB ( dressing* or pad or pads or gauze or tulle or film or bead or foam* or non-adherent or non adherent or hydrocolloid* or alginat* or hydrogel* )

S2 (MH "Alginates")

S1 (MH "Bandages and Dressings+")

Appendix 6. Cochrane tool for assessing risk of bias

1. Was the allocation sequence randomly generated?

Low risk of bias

The investigators describe a random component in the sequence generation process such as: referring to a random number table; using a computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots.

High risk of bias

The investigators describe a non-random component in the sequence generation process. Usually, the description would involve some systematic, non-random approach, for example: sequence generated by odd or even date of birth; sequence generated by some rule based on date (or day) of admission; sequence generated by some rule based on hospital or clinic record number.

Unclear

Insufficient information about the sequence generation process provided to permit a judgement of low or high risk of bias.

2. Was the treatment allocation adequately concealed?

Low risk of bias

Participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomisation); sequentially-numbered drug containers of identical appearance; sequentially-numbered, opaque, sealed envelopes.

High risk of bias

Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: use of an open random allocation schedule (e.g. a list of random numbers); assignment envelopes without appropriate safeguards (e.g. envelopes were unsealed, non-opaque, or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.

Unclear

Insufficient information provided to permit a judgement of low or high risk of bias. This is usually the case if the method of concealment is not described, or not described in sufficient detail to allow a definite judgement, for example if the use of assignment envelopes is described, but it remains unclear whether envelopes were sequentially numbered, opaque and sealed.

3. Blinding - was knowledge of the allocated interventions adequately prevented during the study?

Low risk of bias

Any one of the following:

  • No blinding, but the review authors judge that the outcome and the outcome measurement are not likely to be influenced by lack of blinding.

  • Blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, but outcome assessment was blinded and the non-blinding of others unlikely to introduce bias.

High risk of bias

Any one of the following:

  • No blinding or incomplete blinding, and the outcome or outcome measurement is likely to be influenced by lack of blinding.

  • Blinding of key study participants and personnel attempted, but likely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, and the non-blinding of others likely to introduce bias.

Unclear

Either of the following:

  • Insufficient information to permit judgement of low or high risk of bias.

  • The study did not address this outcome.

4. Were incomplete outcome data adequately addressed?

Low risk of bias

Any one of the following:

  • No missing outcome data.

  • Reasons for missing outcome data are unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).

  • Missing outcome data are balanced in numbers across intervention groups, with similar reasons for missing data across groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with the observed event risk is not enough to have a clinically relevant impact on the intervention effect estimate.

  • For continuous outcome data, a plausible effect size (difference in means or standardised difference in means) among missing outcomes is not enough to have a clinically relevant impact on the observed effect size.

  • Missing data have been imputed using appropriate methods.

High risk of bias

Any one of the following:

  • Reason for missing outcome data are likely to be related to the true outcome, with either an imbalance in numbers or reasons for missing data across intervention groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with the observed event risk is enough to induce clinically relevant bias in the intervention effect estimate.

  • For continuous outcome data, a plausible effect size (difference in means or standardised difference in means) among missing outcomes is enough to induce a clinically relevant bias in the observed effect size.

  • 'As-treated' analysis done with a substantial departure of the intervention received from that assigned at randomisation.

  • Potentially inappropriate application of simple imputation.

Unclear

Either of the following:

  • Insufficient reporting of attrition/exclusions to permit a judgement of low or high risk of bias (e.g. number randomised not stated, no reasons for missing data provided).

  • The study did not address this outcome.

5. Are reports of the study free of suggestion of selective outcome reporting?

Low risk of bias

Either of the following:

  • The study protocol is available and all of the study’s prespecified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified way.

  • The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were prespecified (convincing text of this nature may be uncommon).

High risk of bias

Any one of the following:

  • Not all of the study’s prespecified primary outcomes have been reported.

  • One or more primary outcomes is/are reported using measurements, analysis methods, or subsets of the data (e.g. subscales) that were not prespecified.

  • One or more reported primary outcomes was/were not prespecified (unless clear justification for their reporting is provided, such as an unexpected adverse effect).

  • One or more outcomes of interest in the review is/are reported incompletely so that they cannot be entered in a meta-analysis.

  • The study report fails to include results for a key outcome that would be expected to have been reported for such a study.

Unclear

Insufficient information provided to permit a judgement of low or high risk of bias. It is likely that the majority of studies will fall into this category.

6. Other sources of potential bias

Low risk of bias

The study appears to be free of other sources of bias.

High risk of bias

There is at least one important risk of bias. For example, the study:

  • had a potential source of bias related to the specific study design used; or

  • has been claimed to have been fraudulent; or

  • had some other problem.

Unclear

There may be a risk of bias, but there is either:

  • insufficient information to assess whether an important risk of bias exists; or

  • insufficient rationale or evidence that an identified problem will introduce bias.

What's new

DateEventDescription
15 December 2016New search has been performedFor this second update, glue-as-a-dressing has been added as an intervention to the review. An update search has been run covering existing interventions and the new glue as dressing intervention. GRADE assessment has also been undertaken throughout the review and 'Summary of findings' tables added. Nine new studies have been included.
15 December 2016New citation required but conclusions have not changedNo change to conclusions.

History

DateEventDescription
8 January 2015AmendedExternal sources of support updated.
31 July 2014New citation required but conclusions have not changedNo change to conclusions
31 July 2014New search has been performedFirst update. Four new trials added (Bennett 2013; Burke 2012; Martin-Trapero 2013; Ravnskog 2011)
14 March 2005New citation required and conclusions have changedSubstantive amendment

Contributions of authors

Jo Dumville co-ordinated the review, extracted data and checked the quality of data extraction, undertook and checked quality assessment, analysed and interpreted data,  performed and checked the quality of the statistical analysis, completed the first draft of the review, performed part of the writing or editing, made an intellectual contribution to the review, approved the final version prior to submission, wrote to trial authors/experts/companies and is guarantor for the review and the review update.

Trish Gray contributed to the previous update of this review, checked the quality of data extraction, undertook and checked quality assessment, and checked quality of statistical analysis, performed part of the writing or editing, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Catherine Walter performed previous work that was the foundation of the current review.

Catherine Sharp performed previous work that was the foundation of the current review.

Tamara Page performed previous work that was the foundation of the current review.

Rhiannon Macefield contributed to the update of this review, checked the quality of data extraction, undertook and checked quality assessment, and checked quality of statistical analysis, performed part of the writing or editing, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Natalie Blencowe contributed to the update of this review, checked the quality of data extraction, undertook and checked quality assessment, performed part of the writing or editing, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Thomas KG Milne contributed to the update of this review, checked the quality of data extraction, undertook and checked quality assessment, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Barnaby Reeves contributed to the update of this review, checked the eligibility of additional studies, performed part of the writing or editing, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Jane Blazeby contributed to the update of this review, checked the quality of data extraction, performed part of the writing or editing, made an intellectual contribution to the review update, and approved the final version of the review update prior to submission.

Contributions of editorial base

Nicky Cullum (Editor): edited the review and the updated reviews, advised on methodology, interpretation and review content. Approved the final review and the updated reviews prior to submission.
Gill Rizzello and Sally Bell-Syer (Managing Editors) : co-ordinated the editorial process. Edited the review and updated reviews.
Ruth Foxlee designed the search strategy and Reetu Child ran the searches for this updated review.

Declarations of interest

Jo Dumville: I receive research funding from the NIHR for the production of systematic reviews focusing on high priority Cochrane reviews in the prevention and treatment of wounds.

Trish Gray: none known

Catherine J Walter: none known.

Catherine Sharp: none known.

Tamara Page: none known.

Rhiannon Macefield: none known.

Natalie Blencowe: none known.

Thomas KG Milne: none known.

Barnaby Reeves is funded (both part salary and research consumables) in part by the NIHR Bristol Cardiovascular Biomedical Research Unit.

Jane Blazby: none known.

Sources of support

Internal sources

  • Royal Adelaide Hospital, Adelaide, South Australia, Australia.

  • Division of Nursing, Midwifery & Social Work, School of Health Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester, UK.

External sources

  • This project was supported by the National Institute for Health Research, via Cochrane Infrastructure and Programme Grant funding (NIHR Cochrane Programme Grant 13/89/08 - High Priority Cochrane Reviews in Wound Prevention and Treatment) to Cochrane Wounds. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Systematic Reviews Programme, NIHR, NHS or the Department of Health, UK.

  • The National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care (NIHR CLAHRC) Greater Manchester, UK.

Differences between protocol and review

As a result of feedback from the peer referees the title of this review has been changed from: Wound dressings for surgical sites; to: Dressings for the prevention of surgical site infection.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Bennett 2013

Methods2-arm RCT undertaken in the USA
ParticipantsWomen undergoing a caesarian section
Interventions

Group A: standard soft cloth (MediporePad, 3M) (n = 262 total included in trial analysis = 236)

Group B: silver ion-eluting dressings (Silverlon, Argentum Medical) (n = 262 total included in trial analysis = 239).

"The study population included a total of 524 women who consented to participate and met inclusion criteria; 475 cases were analyzed." Details from the trial author suggest that the trial had equal numbers in each arm. Thus for our analysis, in order to remain in line with our missing data methodology, we have assumed 262 in each arm.

Outcomes

Primary review outcome: SSI (signs of infection - defined as an infection involving only the skin or subcutaneous tissue that occurred within the first 30 days after a surgical procedure - from author)

Secondary review outcomes: costs (of dressings USD - no further details on data collection reported)

Notes

Trial outcome data: see Table 3

Follow-up: participants were evaluated for signs of infection during their hospitalisation, and again at a visit made one-week postpartum.

Conference abstract - author contacted for more information

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "A randomised block design using block sizes of 4 or 6 to ensure that an equal number of subjects were randomly assigned to each arm" - we know that the sequence was computer generated from author correspondence.

Comment: adequate

Allocation concealment (selection bias)Unclear riskDetails unclear
Blinding (performance bias and detection bias)
All outcomes
High riskNone - author correspondence
Incomplete outcome data (attrition bias)
All outcomes
High risk

Quote: "The study population included a total of 524 women who consented to participate and met inclusion criteria; 475 cases were analyzed."

Further information from the author: 524 patients were consented, randomised meeting inclusion criteria [sic]; 475 cases were analysed with 49 participants excluded due to protocol deviations and missing data.

Comment: text suggests that more participants were randomised than analysed.

Selective reporting (reporting bias)Low riskKey outcome reported.
Other biasLow riskNone

Biffi 2012

Methods2-arm RCT conducted in Italy
Participants

121 participants undergoing elective surgery for colorectal cancer

Inclusion criteria: undergoing elective surgery for colorectal cancer by laparotomic approach

Exclusion criteria: history of allergy to dressing components; evidence of active infection at, or adjacent to, the operative site; coagulopathy (defined as platelet count < 50,000 cells/μL or a prothrombin time > 18 seconds); intestinal obstruction; active bowel bleeding; life expectancy < 6 months; inability to give written informed consent; or a programme of minimally invasive surgery planned (laparoscopy or robot-assisted)

Interventions

Group A (n = 62): silver hydrofibre dressing (Aquacel Ag, ConvaTec)

Group B (n = 59): standard absorbant dressing (Mepore, Molnlycke Health Care, Gothenburg, Sweden)

All participants received a preoperative scrub and then painting with an aqueous solution of 10% povidone iodine, mechanical bowel preparation, and antibiotic prophylaxis in agreement with predefined protocols.

Outcomes

Primary review outcomes: SSI (clinical assessment)

Secondary review outcomes: none

Notes

Follow-up: 30 days

We contacted the author about methods

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "To help match the two groups and address potential inter-hospital differences, randomization was stratified by hospital with the use of computer-generated randomization numbers without blocking."

Comment: adequate

Allocation concealment (selection bias)Low risk

Quote: "In order to maintain the double-blind characteristic of this trial, some actions were taken. First, the generator of the assignment was a data manager, who was separated from the executor."

Comment: not clear if the executor of randomisation had access to the full randomisation schedule or was separate from it at point of randomisation. However, the staff were blinded to treatment and the separation was confirmed by the trial author.

Blinding (performance bias and detection bias)
All outcomes
Low risk

Quote: "The Aquacel Ag Hydrofiber dressing was covered by a common wound dressing in the experimental arm, whereas a double common dressing was applied to patients of the control group to blind the patient, the nursing and the medical staff and the independent data collector as to the nature of the dressing used.

Whenever SSI was suspected or diagnosed, clinically relevant microbiologic samples were cultured. Investigators, who were unaware of the patients’ group assignments, assessed the seriousness of all adverse events and determined whether they were related to the trial."

Comment: blinded outcome assessment conducted.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskFlow chart shows that 58/62 participants randomised to the intervention arm (4 lost to follow-up) and 54/59 randomised to control arm were analysed (5 lost). Less than 10% lost in each arm, the impact of this loss unclear.
Selective reporting (reporting bias)Low riskNone noted. Protocol not obtained.
Other biasLow riskNone noted based on available information.

Burke 2012

Methods2-arm RCT, undertaken in single hospital centre in Ireland
Participants

People undergoing elective total hip replacement (THR) and total knee replacement (TKR) (n = 124)

Exclusion criteria:people undergoing revision surgery; taking immune-suppressants (e.g. methotrexate); with chronic skin conditions (e.g. eczema, psoriases); with trophic skin changes (e.g. diabetes, peripheral vascular disease)

Interventions

Group A (n = 62: 35 THR and 27 TKR): absorbent dressing (Mepore, Mölnlycke Health Care)

Group B (n = 62: 35 THR and 27 TKR): Jubilee dressing (hydrofiber inner layer (Aquacel, ConvaTec) with a viscoelastic hydrocolloid outer layer (DuoDerm, ConvaTec))

The TKR participants in both groups also had a layer of wool and crepe applied from the suprapatellar region of the knee to below the tibial tuberosity. This was removed on day 1 after surgery. Dressings were changed only when a > 50% strike through of the inner layer was visible.

Outcomes

Primary review outcome: SSI (not defined, although an erythematous, indurated wound with persistent copious discharge was taken to be suggestive of a deep SSI. Number of wounds with inflammation was also extracted, but inflamed wounds were not classed as infected in this trial)

Secondary review outcomes: cost (number of dressing changes required and average hospital stay)

Notes

Trial outcome data: see Table 3

Follow-up: not reported

Given the use of a hydrofibre dressing as the contact layer here, we treated this intervention as a hydrofibre dressing.

We contacted the author about methods.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "Patients were selected using the block randomisation method to have either the Jubilee dressing or a traditional adhesive dressing applied to their surgical wound." Author confirmed that a computer-generated block randomisation was used, it was an Internet based program.

Comment: details unclear

Allocation concealment (selection bias)Unclear riskUnable to make a decision based on available information.
Blinding (performance bias and detection bias)
All outcomes
Unclear risk

Quote: "The outcomes were all assessed by the same tissue viability nurse and not by the medical/team involved in the surgery. She was not involved in the randomisation process."

Comment: unclear if the nurse was blinded to treatment

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll randomised participants were included in the analysis.
Selective reporting (reporting bias)Low riskAll listed outcomes were reported - there were no outcomes that were obviously missing.
Other biasLow riskNot noted

Cosker 2005

Methods3-arm RCT, undertaken in the UK
ParticipantsPeople undergoing hip or knee surgery (trauma and elective cases). Those who failed to give consent, or who had dressing allergies were excluded. 100 participants were randomised to each dressing group (total n = 300).
Interventions

Group A (n = 100): standard absorbent dressing (Primapore, Smith & Nephew)
Group B (n = 100): transparent film dressing and pad (Tegaderm and pad, 3M Healthcare)
Group C (n = 100): film dressing (Opsite Post-Op, Smith & Nephew)

Stated that all dressings were used according to manufacturers' instructions, but no further details provided.
We merged Groups B and C and treated this as a 2-arm trial in this review.

OutcomesPrimary review outcome: SSI (not defined); trial reported "numbers of patients in each group who progressed to overt infection" and required antimicrobial therapy.
Secondary review outcomes: not reported
Notes

Trial outcome data: see Table 3

Included some implants (i.e. screws)

Follow-up not reported

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "Randomisation was effected by indicating the dressing in an envelope, which was opened by the theatre sister at the end of the operation."

Comment: unclear how sequence was generated.

Allocation concealment (selection bias)Unclear riskSee above. The paper notes that participants in the film dressing (Opsite) group were "significantly older" than in the other groups. No data presented.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskThere were 14 exclusions and it was unclear whether these were pre- or post-randomisation.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes were reported.
Other biasHigh riskIt seems that there was baseline imbalance in age, but no data were reported beyond the details in the text.

De Win 1998

Methods2-arm RCT undertaken in Belgium
ParticipantsPeople > 18 years undergoing neuro- or cardiovascular surgery
InterventionsGroup A (n = 6): absorbent dressing (Mepore, Mölnlycke Health Care)
Group B (n = 8): transparent film dressing and pad (Tegaderm and pad, 3M Healthcare)
Dressing changes followed the in-house wound care protocol (not described).
Outcomes

Primary review outcome: SSI (not defined)

Secondary review outcomes: cost (mean total cost of dressings)

Notes

Trial outcome data: see Table 3

Report of interim analysis. Trial plans to recruit 60 people, paper reported the results of the 14 participants who had finished the trial at the time of writing. No further publications found.
Follow-up: participants enrolled for 7–10 days with dressing inspected every day.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided in paper.
Allocation concealment (selection bias)Unclear riskNo information provided in paper.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo information provided in paper.
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll randomised participants were included in the analysis.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes were reported.
Other biasHigh riskMultiple wounds per participant not taken into account.

Dickinson Jennings 2015

Methods3-arm RCT undertaken in the USA
Participants

351 participants undergoing sternotomy

Inclusion criteria: > 21 years of age; undergoing cardiac surgery requiring sternotomy incisions; hospitalised at the trial setting; English-speaking; able to understand and give consent; have their surgeon approve participation; and not be sensitive to silver or alginates

Interventions

Group A (n = 117): standard sterile dressing (Primapore, Smith & Nephew). This dressing was left in place for either 24 or 48 hours.

Group B (n = 116): metallic silver dressing (Acticoat Post-Op, Smith & Nephew). This dressing was left in place over the incision for 5 days.

Group C (n = 118): ionic silver dressing (Transeal, DeRoyal). This dressing was left in place over the incision for 5 days.

All participants received the same skin preparation and antibiotic regime.

Before placement of the silver dressings, a liquid barrier product (Skin Prep, ConvaTec) was applied to the area around the participant’s incision and permitted to dry to enhance adherence.

All participants received intravenous antibiotics within the appropriate timeframe before surgery.

Outcomes

Primary review outcome: SSI (not defined)

Secondary review outcomes: ease of removal (5-point scale: 1 = very easy, 2 = moderately easy, 3 = neither easy nor difficult, 4 = moderately difficult and 5 = very difficult); pain (comfort) (0-10 scale with 0 signifying no pain and 10 signifying maximum pain).

Notes

Trial outcome data: see Table 3

Follow-up: 30 days

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "The PI used a statistician-generated, random numbers table to assign participants to each of the 3 dressing groups."

Comment: considered adequate

Allocation concealment (selection bias)Unclear risk

Quote: "Following randomization, the PI took the appropriate dressing to the operating room and communicated the dressing assignment directly to the nursing staff. Participants were not told of their group assignment until they awakened after surgery."

Comment: not clear if PI was aware of sequence until point of randomisation

Blinding (performance bias and detection bias)
All outcomes
High risk

Quote: "Due to the nature of the dressings, no aspect of this trial was blinded."

Comment: no blinded outcome assessment was undertaken

Incomplete outcome data (attrition bias)
All outcomes
Unclear risk

Quote: "Thirty-six participants were withdrawn from the trial because they did not wear their assigned dressing until the appropriate removal time due to additional surgeries or inadvertent removal."

Comment: all participants should have been included in the trial regardless of adherence to protocol. The impact of this incomplete outcome data on findings is unclear: 11 participants were removed from Group A, 11 from Group B, and 14 from Group C.

Selective reporting (reporting bias)Low riskGiven information presented in paper, all prespecified outcomes reported.
Other biasLow riskNone noted

Gardezi 1983

Methods2-arm RCT undertaken in Pakistan
Participants

People undergoing a general surgical operation - 9 different types

Exclusion criteria: children < 12 years of age; unconscious or unresponsive people

InterventionsGroup A (n = 50): conventional gauze dressing changed after 48 hours
Group B (n = 50): film dressing (polyurethane membrane) applied immediately postsurgery and left in situ until suture removal (fresh film applied on discharge and left until review at 1 week). No dressing details provided.
Outcomes

Primary review outcome: SSI (not clearly defined); a number of relevant wound features i.e. redness were assessed, but it is not clear how this assessment informed diagnosis.

Secondary review outcomes: pain (no details about how this was measured)

Notes

Trial outcome data: see Table 3

Follow-up: no details provided

Antibiotics were given when infection occurred.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskComment: Pairs of participants were matched (age, sex and physical condition). One of each pair was assigned to each group. However, the authors stated that some pairing was done retrospectively. This makes the randomisation process difficult to understand.
Allocation concealment (selection bias)Unclear riskRandomisation using pairs would be unconcealed, but it is not clear whether this process formed the basis of the allocation method.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
Low riskThere was no reported loss to follow-up.
Selective reporting (reporting bias)Low riskGiven the information presented in paper, all prespecified outcomes reported.
Other biasUnclear riskLimited baseline information and unclear randomisation process

Hewlett 1996

Methods2-arm RCT undertaken in the UK
Participants

People undergoing spinal, orthopaedic or abdominal surgery; in total 77 participants were randomised.

Exclusion criteria: people admitted to hospital for minimally-invasive surgical techniques

InterventionsGroup A (n = 39): absorbent dressing (Mepore, Mölnlycke Health Care)
Group B (n = 37): film dressing (Opsite, Smith & Nephew)
Manufacturers' instructions were followed when applying and removing dressings (no further details provided). Treatment was for a maximum of 10 days.
Outcomes

Primary outcome: not reported.

Secondary outcomes: cost (dressing cost to complete healing)

Notes

Trial outcome data: see Table 3

Follow-up: unclear. Trial information retrieved from a poster report only. Infection not reported.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information provided in poster report.
Allocation concealment (selection bias)Unclear riskNo information provided in poster report.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo information provided in poster report.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo information provided in poster report.
Selective reporting (reporting bias)Unclear riskNo information provided in poster report.
Other biasUnclear riskNo information provided in poster report.

Holm 1998

MethodsRCT undertaken in Denmark
Participants

People undergoing abdominal surgical procedures with an incision > 5 cm

Exclusion criteria: people suffering concomitant underlying disorders that influence the healing process (i.e. HIV, or receiving systemic corticosteroids or chemotherapy), potentially undergoing dirty procedures, or the creation of an enterstoma

InterventionsGroup A (n = 37): absorbent dressing (Mepore, Mölnlycke Health Care) removed 2 days postoperatively (usual routine)
Group B (n = 36): hydrocolloid dressing (Comfeel plus transparent dressing, Coloplast) left on until sutures removed at day 10
No difference in drain usage between groups.
Outcomes

Primary review outcome: SSI (diagnosed in presence of pus, pyrexia and local tenderness)

Secondary review outcomes: cost (number of dressing changes required); scarring (mean width in mm and total cosmetic quality of scar)

Notes

Trial outcome data: see Table 3

Follow-up: average follow-up time was 74.1 days in the absorbent dressing group and 80.2 days in the hydrocolloid group. Cosmetic outcome was assessed at final follow-up 3 months after the operation.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "After informed consent patients were randomised..."

Comment: not enough detail provided to enable us to judge the process.

Allocation concealment (selection bias)Unclear riskNo information provided.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinded for scarring, unclear regarding infection.
Incomplete outcome data (attrition bias)
All outcomes
High riskExcluded post randomisation: 23 (6 deaths, 12 personal reasons (1 due to dressing), 3 re-operation and 2 other). Infection (n = 6) was also classed as a reason for drop out. No ITT analysis.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes were reported.
Other biasUnclear riskLimited baseline data reported, more transverse wounds in the hydrocolloid group.

Kriegar 2011

Methods2-arm RCT conducted in the USA
Participants

110 participants undergoing anticipated colorectal surgery. Both open and laparoscopic operations were included.

Inclusion criteria: anticipated colorectal surgery with an abdominal incision of at least 3 cm

Exclusion criteria: known allergy to silver; signs of abdominal wall infection; condition that would prevent full closure of the skin at the primary operative site or prior abdominal mesh that was not planned to be fully removed at the time of operation; pregnant or breastfeeding women; and people who had received antibiotics within 1 week of surgery

Interventions

Group A (n = 55): sterile gauze held with tape; on discharge participants were instructed to change dressings as needed.

Group B (n = 55): silver nylon dressing; the dressing was designed to stay in place for 7 days.

The wounds were examined 48 hours after surgery. Silver-dressed wounds that had dried before this point were hydrated, and if the gauze had become saturated it was changed.

All participants received preoperative antibiotics 30 to 60 minutes before surgery (ertapenem or alternatives for participants with a penicillin allergy). All perioperative antibiotics were discontinued within 24 hours.

Outcomes

Primary review outcome: SSI (based on CDC classification)

Secondary review outcome: none reported

Notes

Follow-up for 30 days

Author contacted for methods details

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "Randomistion was completed with nQuery software by a blinded statistician using sealed envelopes"

Comment: adequate

Allocation concealment (selection bias)Unclear risk

Quote: "Randomistion was completed with nQuery software by a blinded statistician using sealed envelopes"

Comment: unclear if envelopes were numbered to ensure they were opened sequentially.

Blinding (performance bias and detection bias)
All outcomes
High risk

Quote: "The surgical team was blinded to the surgical dressing until the time of skin closure at the end of the operation. .... determination of whether a wound was infected was made by an unblinded physician."

Comment: not blinded, risk of bias of outcome assessment for SSI (only outcome).

Incomplete outcome data (attrition bias)
All outcomes
Low riskFlow chart shows no loss to follow-up.
Selective reporting (reporting bias)Low riskNone noted. Protocol not obtained.
Other biasLow riskNone noted based on reporting.

Langlois 2015

Methods2-arm RCT undertaken in France
Participants

80 participants undergoing primary THA or TKA

Inclusion criteria: aged 18-95 years; able to understand information; undergoing primary THA or TKA

Exclusion criteria: prior operative local procedure around the joint; past local infection; or advanced cancer

Interventions

Group A (n = 40): sterile gauze held in place with a crepe bandage

Group B (n = 40): hydrofibre dressing (Aquacel, ConvaTec)

In the sterile gauze group, the dressing change was scheduled between days 1and 3 postoperatively, with a second change on the day of discharge. Gauzes were then replaced by a conventional adhesive pad (Mepore, Mölnlycke Health Care, Göteborg, Sweden). In the hydrofibre dressing group, the only change was scheduled for the day of discharge. In both groups, an extra change of dressing was performed in case of saturation with leakage, major loss of adherence, bleeding, or suspected infection.

The postoperative regimen included administration of systemic antibiotics for 48 hours, thromboprophylaxis with low molecular weight heparin for six weeks, and anti-inflammatory medication (ketoprofen, 100 mg/day for 5 days).

Outcomes

Primary review outcome: SSI (not defined further)

Secondary review outcome: scar cosmetic appearance; pain

Notes

Trial outcome data: see Table 3

Follow-up: 6 weeks

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "The patients were randomised using a computer-generated block randomization scheme to have either conventional or hydrofibre dressing."

Comment: adequate

Allocation concealment (selection bias)Unclear risk

Quote: "The randomization was based on the order of patient presentation, so each patient was randomised individually regardless of severity of osteoarthritis and co-morbid situation."

Comment: unclear if allocation was concealed.

Blinding (performance bias and detection bias)
All outcomes
Unclear risk

Quote: "scar cosmetic appearance evaluated six weeks after surgery by a plastic surgeon that was blinded to the dressing used and not involved in the surgical procedures."

Comment: low risk for surgeon scar assessment unclear for other outcomes.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFlow chart suggests all participants analysed.
Selective reporting (reporting bias)Low riskNone noted. Protocol not obtained.
Other biasLow riskNone noted based on reported information.

Law 1987

Methods3-arm RCT undertaken in the UK
ParticipantsPeople undergoing inguinal hernia repair or high saphenous ligation. 170 participants randomised. 4 participants lost to follow-up, but unclear to which group(s) they belonged. No information provided regarding follow-up.
InterventionsGroup A (n = 59): gauze, removed on day 5, or changed if wound was discharging
Group B (n = 54): film dressing (Opsite; Smith & Nephew), removed on day 5. Discharge aspirated through dressing, and new dressing applied, if necessary.
Group C (n = 53): exposed wound (if discharge, covered with gauze for as long as necessary)
OutcomesPrimary review outcome: SSI (not defined)
Secondary review outcome: cost (total dressing cost)
Notes

Trial outcome data: see Table 3

Follow-up: not reported

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "...were randomly allocated to one of three surgical dressing options".

Comment: not enough detail provided to understand process.

Allocation concealment (selection bias)Unclear riskNo details provided in the report.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
Low riskComment: trial notes that 4 participants were lost to follow-up.
Selective reporting (reporting bias)Unclear riskLack of data for certain outcomes such as preference, scarring and comfort.
Other biasUnclear riskNo baseline data presented.

Lawrentschuk 2002

Methods2-arm RCT undertaken in Australia
ParticipantsPeople undergoing elective and emergency hip surgery. The trial stated that there were no exclusion criteria.
InterventionsGroup A (n = 25): non-adherent absorbable dressing (Interpose)
Group B (n = 25): paraffin tulle gras (Jelonet)
In both groups: a compressible, combined dressing was placed immediately over the dressing being evaluated, and an adhesive elastic fabric dressing (Hyperfix) was placed over these 2 dressings.
Dressings were placed with minimal force by the same resident in a standardised fashion, so as not to create tension in the skin. All dressings were sterile and non-medicated.
Wounds were checked at 48 hours - all dressings were replaced after inspection and inspected again at 5 days.
Outcomes

Primary review outcome: SSI (not defined)

Secondary review outcomes: not reported

Notes

Trial outcome data: see Table 3

Follow-up: not reported

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "Patients were randomised into two different groups at the time of skin closure when a computer-generated envelope was opened indicating which dressing to be [sic] used".

Comment: adequate

Allocation concealment (selection bias)Unclear riskSee above. Not clear if sequentially numbered.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo evidence of missing outcome data.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasLow riskNo other biases noted.

Martin-Trapero 2013

Methods2-arm RCT undertaken in Spain
Participants

People diagnosed with cholelithiasis undergoing elective laparoscopic cholecystectomy

Exclusion criteria: > 70 years of age; diabetes; having a fever; and current treatment with immunosuppressants

Interventions

Group A (n = 101): non-occlusive dressing (gauze)

Group B (n = 96): 0.2% polyhexamethylene biguanide (PHMB) dressing

The disinfection of the skin prior to surgery was performed 2 times with a solution of povidone iodine.

A single dose of prophylaxis antibiotics was given at anaesthetic induction.

Metal staples were used to close the surgical wound. Once incisions closed the wound was cleaned with povidone-iodine 0.01% and the gauze or PHMB dressing was applied.

Outcomes

Primary review outcome: SSI (CDC definition)

Secondary review outcomes: none (based on translation)

Notes

Trial outcome data: see Table 3

Information extracted from English abstract and limited translation of methods and results

Follow-up: 30 days

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Based on translation

"....were assigned by an automatic method after the preparation of a spreadsheet (MS Excel) using the function -random tool where the researcher did not know the allocation of the next patient to be included in the study (concealment of random allocation)"

Allocation concealment (selection bias)Low risk

Based on translation

"....were assigned by an automatic method after the preparation of a spreadsheet (MS Excel) using the function -random tool where the researcher did not know the allocation of the next patient to be included in the study (concealment of random allocation)"

Blinding (performance bias and detection bias)
All outcomes
Unclear riskNot able to assess
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNot able to assess
Selective reporting (reporting bias)Unclear riskNot able to assess
Other biasUnclear riskNot able to assess

Michie 1994

Methods2-arm RCT undertaken in the USA
Participants

People undergoing elective plastic and reconstructive surgery resulting in incision(s) not exceeding 200 mm

Exclusion criteria: people with concomitant underlying disorders that might influence healing (e.g. use of corticosteroids, diabetes mellitus with a fasting blood sugar of > 250 mg/dL, or a compromised immunological status)

28 participants with 40 wounds took part in the trial. Participants served as their own controls, with half of each wound covered in a trial dressing.

InterventionsGroup A (n = 28): cotton gauze impregnated with bismuth tribromophenate (Xeroform; Sherwood Medical Company)
Group B (n = 28): hydrocolloid dressing (DuoDerm ExtraThin CGF; Convatec Bristol-Myers Squibb)
Dressings removed at 7-10 days postoperatively (when sutures removed).
Outcomes

Primary review outcome: SSI (not defined)

Secondary review outcomes: scarring (various outcomes); pain (past 48 hours); ease of removal (participant's perception of pain on removal and clinician's opinion as to whether the dressing was easy to remove)

Notes

Trial outcome data: see Table 3

Sponsored by Convatec.

Data given for 28 participants rather than the 40 wounds. The statistical analysis allowed for this by using matched exact tests for proportions and matched asymptotic tests for trend for paired contingency data.

Follow-up: all wounds were evaluated at 2–3 days, 7–10 days, 4 weeks and 7 months postoperatively.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComment: computer-generated randomised table with blocks of 4 used to determine which dressing went to which end of the wound.
Allocation concealment (selection bias)Unclear riskNo details reported.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNot reported. Treating surgeon assessed cosmetic result.
Incomplete outcome data (attrition bias)
All outcomes
Low riskOnly 1 participant lost to follow-up.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasLow riskNone noted

Moshakis 1984

Methods2-arm RCT undertaken in the UK
ParticipantsPeople undergoing the excision of a breast lump
InterventionsGroup A (n = 59): dry gauze; 4–6 gauze dressings secured in place by 4 cm strips of tape (Transpore or Elastoplast, 3M Healthcare). Removed 1 day postoperatively and inspected; drain removed; a new dressing applied. Participants provided with dressings to take home, if further changes required.
Group B (n = 61): transparent film (polyurethane membrane) dressing (Tegaderm, 3M Healthcare) left intact until day 6–8 for suture removal. If drain present, dressing was split along the length of the drain and it was removed. Any serious fluid collection was aspirated, and puncture covered with Transpore.
Outcomes

Primary review outcome: not reported

Secondary review outcomes: pain (assessed by participant on a linear scale); acceptability (assessed by participant on a linear scale also assessed by nurse on the same scale). Cost, scarring and ease of removal not reported.

Notes

Trial outcome data: see Table 3

Follow-up: nurse assessment of the wound took place before discharge, normally 1 day postoperatively. Participants gave their wound assessments at an outpatient visit (normally 6-8 days postoperatively).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High risk

Quote: "..they were randomly allocated to receive.." However, some patients were undergoing excision of bilateral breasts lumps. In this case each wound was allocated to a different dressing. Therefore, some participants were their own control and some were not.

Comment: unclear process

Allocation concealment (selection bias)Unclear risk"To diminish bias, allocation of the dressing to each patient was not known to the surgeon until the end of the operation"
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskLoss to follow-up: 5 at outpatient follow-up
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasHigh riskLack of baseline data. Analysis did not acknowledge the lack of independence in wounds on the same person.

Ozaki 2015

Methods2-arm RCT undertaken in the USA (2 medical centres)
Participants500 adults were randomised. Eligible participants were undergoing an open (incision below the inguinal ligament) non-emergency surgical procedure for peripheral vascular disease involving arteries or bypass grafts, with the anticipation that all incisions would be closed.
Interventions

Group A (n = 250): standard gauze

Group B (n = 250): silver alginate dressings

No other dressing details provided.

This original operating room dressing remained in situ until gross soiling, clinical need to remove, or postoperative day 3, whichever came first. Subsequent care was at the provider’s discretion.

The wound-closure technique was at the discretion of the surgeon. Cyanoacrylate tissue adhesives were considered as dressings and were not permitted.

Outcomes

Primary review outcome: assessment of wound complication which included SSI at 30 days (defined as no wound complication, superficial SSI or deep SSI - noted that National Surgical Quality Improvement Program definitions were used).

Secondary review outcomes: none reported

Notes

Trial outcome data: see Table 3

Noted that most cases were clean surgery (notes 25/500 participants had wounds classified as clean/contaminated)

Follow-up: 30 days

We contacted the author to ask about methods

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "Patients were randomised in the operating room by block design after wound closure was completed but before any dressing was applied."

Quote from author: "Block 16 randomization per site. Generated via RAND in SAS"

Comment: adequate

Allocation concealment (selection bias)Low risk

Quote from author: "Patients and providers were blinded until time of reveal, which was at the end of the case (patient under anaesthesia) when the dressing is needed."

Comment: adequate

Blinding (performance bias and detection bias)
All outcomes
High risk

All outcomes

Quote from paper: "In addition, although the patients and providers were not formally blinded to the type of original postoperative dressing, the study physicians generally reported an inability to recall which dressing the patient had received at the late follow-up visits."

Quote from author: "No one [sic] who assessed outcome was formally blinded, though in reality the evaluating clinicians noted that they frequently did not recall which early post-operative dressing the patient had at 2 and 4 weeks."

Comment: blinded outcome assessment was not conducted

Incomplete outcome data (attrition bias)
All outcomes
Low riskIn total 7/500 participants (3 in the silver group and 4 in the gauze group) were lost to follow up.
Selective reporting (reporting bias)Unclear riskStudy reported and listed a number of other outcomes that were collected, including length of stay and EQ-5D, but these data were not reported in the paper.
Other biasLow riskNone noted

Persson 1995

Methods2-arm RCT undertaken in Sweden
ParticipantsPeople having surgery for benign GI disease incurring a postoperative hospital stay of at least 5 days. 68 participants randomised. 7 participants excluded post-randomisation (6 due to wrong dressing, 1 refused to be left without a dressing), but details of their allocation were not provided.
InterventionsGroup A (n = 30): exposed wounds initially covered with an absorbent dressing removed morning after surgery.
Group B (n = 31): occlusive hydrocolloid dressing (DuoDerm E, Convatec/Bristol-Myers Squibb) left in place until hospital discharge, or wound infection developed.
OutcomesPrimary review outcome: SSI (not defined)
Secondary review outcomes: pain (estimated from graphical representation of linear scale); acceptability (from participants' perception)
Notes

Trial outcome data: Table 3

Follow-up: until discharge. No further information provided.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "On admission to the ward, they were randomised to have their wounds covered with a dressing or exposed..."

Comment: limited detail provided to assess whether approach was adequate.

Allocation concealment (selection bias)Unclear riskNo details mentioned in the report.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
High risk7 randomised participants excluded (6 because wrong dressing applied and 1 who refused to have wound left uncovered).
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasUnclear riskAlso varied timing as well as dressing type. No baseline table presented, but median age was 43 years in the dressing group and 36 years in the open group.

Phan 1993

Methods2-arm RCT undertaken in Belgium
Participants

People with stage II, III and IV or recurrent head and neck cancer selected for extensive surgery (with or without radical neck dissection and flap reconstruction)

Exclusion criteria: undergoing simple laryngectomy, partial glossectomy or pharyngoplasty.

In total 207 participants randomised; 102 to receive the standard gauze (86 evaluated) and 105 to the ointment group (93 evaluated).

Interventions

Group A (n = 86): standard gauze dressing (not named). Changed twice daily with wound cleaning using alcoholic chlorhexidine solution
Group B (n = 93): surgical wound ointment with pure Vaseline (Qualifar) without gauze dressing. Vaseline was removed twice a day using sterile gauze, followed by cleaning of the wound with alcoholic chlorhexidine solution before application of a new cover with pure Vaseline.

Duration for which the dressings remained in place was not recorded.

OutcomesPrimary review outcome: SSI (defined as a clinically documented infection localised at the surgical site and presenting with a purulent discharge with a severe inflammatory reaction > 5 cm of erythema and induration)
Secondary review outcomes: not reported
Notes

Trial outcome data: seeTable 3

32 participants in each group received antibiotic treatment.

Follow-up: 20 days

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "The study was prospective and randomised".

Comment: limited detail provided to assess

Allocation concealment (selection bias)Unclear riskQuote: "Randomization was performed using sealed envelopes"
Comment: not clear whether envelopes were numbered, or another method was employed to ensure concealment, so judged as unclear.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
High risk26 participants excluded because lower GI surgery took place, surgery cancelled, protocol violation, participants could not be evaluated due to death or other circumstances.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasUnclear riskDifferences at baseline: more stage IV cases in gauze group compared with Vaseline group (54% vs 39%) - possibly due to exclusions?

Politano 2011

Methods2-arm RCT conducted in the USA
Participants145 participants undergoing vascular reconstructions, documentation of other details limited.
Interventions

Group A (n = 75): standard dressing (Primapore, Smith & Nephew)

Group B (n = 70): silver impregnated dressing (Therabond 3D, Choice Therapeutics)

Outcomes

Primary review outcome: SSI (not defined)

Secondary review outcomes: none reported

Notes

Trial outcome data: see Table 3

Abstract only - only limited data available to extract.

Unable to find author contact details

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskUnclear - no details reported
Allocation concealment (selection bias)Unclear riskUnclear - no details reported
Blinding (performance bias and detection bias)
All outcomes
Unclear riskUnclear - no details reported
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskUnclear - no details reported
Selective reporting (reporting bias)Unclear riskUnclear - no details reported
Other biasUnclear riskUnclear - no details reported

Prather 2011

Methods2-arm RCT
Participants110 participants undergoing colorectal surgery (no further details provided).
Interventions

Group A (n = 54): gauze

Group B (n = 56): silver nylon

Outcomes

Primary review outcome: not reported

Secondary review outcomes: costs (costs of pain medication were calculated); pain (each day the level of pain was assessed in the morning and at night). Also reported that scores were collected at 30 days, but data not reported. A 0 to 10 pain scale was used where 0 = no pain and 10 = the worst pain imaginable.

Notes

Trial outcome data: see Table 3

Extraction based on abstract only - limited information available

Trial outcome data reported narratively in text

Suggested that follow-up was 30 days, but only reported data at 7 days

Unable to find author contact details

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskUnclear - no details reported
Allocation concealment (selection bias)Unclear riskUnclear - no details reported
Blinding (performance bias and detection bias)
All outcomes
Unclear riskUnclear - no details reported
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskUnclear - no details reported
Selective reporting (reporting bias)Unclear riskUnclear - no details reported
Other biasUnclear riskUnclear - no details reported

Ravnskog 2011

Methods2-arm RCT, undertaken in Norway
ParticipantsPeople undergoing primary hip arthroplasty
Interventions

Group A (n = 100): alginate dressing (Tegaderm Alginate, 3M)

Group B (n = 100): hydrofibre dressing (Aquacel, ConvaTec)

In theatre, participants received either a hydrofibre dressing (10 cm x 10 cm) or an alginate dressing (10 cm x 10 cm or 10 cm x 20 cm), both of which were folded to achieve a 3-layer deep dressing. Both dressings were covered with the same adhesive polyurethane film (Mepore, Mölnlycke Healthcare).

Outcomes

Primary review outcome: not reported

Secondary review outcomes: acceptability (measured as pain/discomfort during wear); ease of removal (pain at removal recorded using a VAS)

Notes

Trial outcome data: see Table 3

Follow-up: not reported. Also reported on skin damage - data not extracted for this review.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "Two members of hospital staff, who were in no other way connected to the trial, prepared the same number of cards with either ‘Aquacel’ or ‘Alginate’ written on them, and then put them into opaque sealed envelopes. Randomisation took place in the operating theatre, after incision, when the scrub nurse randomly chose and opened one of these sealed envelopes."

Comment: difficult to be sure that the sequence was completely random.

Allocation concealment (selection bias)Low risk

Quote: "Two members of hospital staff, who were in no other way connected to the trial, prepared the same number of cards with either ‘Aquacel’ or ‘Alginate’ written on them, and then put them into opaque sealed envelopes. Randomisation took place in the operating theatre, after incision, when the scrub nurse randomly chose and opened one of these sealed envelopes."

Comment: method should preserve allocation concealment. Sequential numbering of the envelopes was not reported - this would have been reassuring.

Blinding (performance bias and detection bias)
All outcomes
High risk

Quote: "Patients were blinded to the dressing they received. Total blinding was not possible among staff as there is a slight visual difference between the two dressings."

Comment: no blinded outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll data reported
Selective reporting (reporting bias)Low riskNone noted
Other biasLow riskNone noted

Rohde 1979

Methods2-arm RCT undertaken in Germany
ParticipantsPeople undergoing elective abdominal procedure within a general surgery department
InterventionsGroup A (n = 46): conventional dressing (Fixomull-stretch; Beiersdorf AG)
Group B (n = 44): transparent drape (Opsite, Folie B. Braun Dexon GmbH, Spangenberg)
Outcomes

Primary review outcome: SSI (unclearly defined)

Secondary review outcomes: cost (per participant); pain (comfort); ease of removal (not defined)

Notes

Trial outcome data: see Table 3

Translated paper

Follow-up: not clear

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk'Treatment' or 'control' cards were opened shortly after operation to determine which dressing should be applied.
Allocation concealment (selection bias)Unclear riskNot translated.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNot translated.
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNot translated.
Selective reporting (reporting bias)Unclear riskNot translated.
Other biasUnclear riskNot translated.

Ruiz-Tovar 2015

Methods3-arm RCT undertaken in Spain (only 2 arms relevant to this review and considered here)
Participants

98 people undergoing colorectal surgery (clean-contaminated)

Inclusion criteria: diagnosis of colorectal neoplasms and plans to undergo an elective operation with curative aims

No exclusion criteria listed.

Interventions

Group A (n = 49): gauze and plastic adhesive tape, removed on day 5 as per protocol, or if SSI suspected

Group B (n = 49): silver-containing dressing (no further details), removed on day 5 as per protocol, or if SSI suspected

All wounds: perioperative systemic antibiotics (cefuroxime 1500 mg and metronidazole 1500 mg; single dose preoperatively, within 30 minutes of incision, and redosed after 4 hours if the surgery exceeded 4 hours) were used in all groups. No mechanical bowel preparation took place in any participant. An aqueous solution of 10% povidone-iodine was applied to the skin preoperatively. Skin closure was with staples after which povidone-iodine solution was applied.

All dressings were covered with a further standard dressing to blind participants, health professionals and data collectors.

Outcomes

Primary review outcome: SSI (SSI was suspected when the participant presented with fever, a red, painful, and tender region adjacent to the dressing, or the dressing was impregnated with a liquid that indicated purulent discharge - any of these symptoms led to removal of the trial dressing. SSI was formally diagnosed using CDC criteria).

Secondary review outcomes: none

Notes

Trial outcome data: see Table 3

Length of follow-up was 30 days

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

Quote: "Patients were randomly assigned in a 1:1:1 allocation scheme using a random-number table into 3 groups"

Comment: considered adequate

Allocation concealment (selection bias)Low risk

Quoate: "In order to maintain the blind characteristic of this trial, some actions were taken. First, the generator of the assignment was a data manager, who was separated from those who applied dressings"

Comment: considered adequate

Blinding (performance bias and detection bias)
All outcomes
Low riskQuote: "In order to maintain the blind characteristic of this trial, some actions were taken. First, the generator of the assignment was a data manager, who was separated from those who applied dressings (scrub nurses in the operating room at the end of each procedure). The groups received a common secondary dressing which blinded the medical staff, and the independent data collector ... Once the dressing was removed, the epidemiology nurse who diagnosed SSI on the basis of criteria developed by the Centers for Disease Control and Prevention (CDC) still remained unaware of the group assignments because she was not present at the time of dressing removal, and she evaluated the wound later"
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants randomised appear to have been included in the analysis.
Selective reporting (reporting bias)Low riskNone noted, but trial protocol not obtained.
Other biasLow riskNone noted

Shinohara 2008

Methods2-arm RCT undertaken in Japan
Participants

People undergoing operations for GI surgery including gastric, duodenal, pancreatic and biliary surgery, and surgery on the colon and rectum

Exclusion criteria: anal, perianal, peritonitis and emergency operations

Follow-up: dressings evaluated postoperatively by daily wound inspection until participant discharged. Cosmetic outcome assessed at 3 months after surgery. All participants were treated with cephamycin antibiotic postoperatively.

InterventionsGroup A (n = 71): conventional gauze, removed postoperatively day 7
Group B (n = 63): occlusive hydrocolloid dressing (Karayahesive, Alcare) left in place until sutures removed 7 days postoperatively
Dressings were changed if the dressing slipped or leaked.
Dressings were discontinued if wound infection developed (defined as pus, pyrexia and local tenderness).
Outcomes

Primary outcome: SSI (postoperative tissue and wound complications were defined as SSIs (superficial or deep wound infection, wound abscess) based on CDC guidelines for prevention of SSI).

Secondary outcomes: cost (of dressing per participant); scarring: (mean scar width)

Notes

Trial outcome data: see Table 3

Mean follow-up time noted as 90 days in both groups.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo details provided in report on methods.
Allocation concealment (selection bias)Unclear riskNo details provided in report on methods.
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo mention of blinding in the trial report.
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo evidence of missing outcome data.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasLow riskNo other biases noted.

Siah 2011

Methods2-arm RCT undertaken in Singapore
Participants

166 people undergoing various types of elective colorectal surgery

Inclusion criteria: people undergoing abdominal surgery with incisions that penetrated the viscera

Exclusion criteria: people who received non-standard prophylaxis in the week prior to surgery or were listed as ‘dangerously ill’ and potentially at risk of dropping out of the trial before the end of its 4-week duration; those on intensive immunosuppressant treatment, high-dose steroids, radiation or chemotherapy or with a known allergy to silver; those who did not receive proper bowel preparation due to an emergency

Interventions

Group A (n = 83): wound exposure; a sterile, highly absorbent, low-adherent pad was affixed immediately postoperatively by a low allergy, acrylic adhesive, spread onto the non-woven backing surface, by the operating staff, immediately after wound closure. The dressing was then removed the next day (first postoperative day), in the surgical ward, and the wound was left exposed

Group B (n = 83): ionic silver-containing dressing (Aquacel Ag, ConvaTec, Wales, UK). Each dressing was covered with an adhesive skin contact layer. The dressing was left in place until discharge - normally at 7 days

Antibiotic prophylaxis was given, as per standard practice.

Outcomes

Primary review outcome: SSI (CDC criteria)

Secondary review outcome: none reported.

Notes

Trial outcome data: see Table 3.

Follow-up: 30 days

We contacted the author for information on methods

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "Patients included in this study were randomised into their respective group by means of drawing a sealed envelope stating either ‘control’ group or ‘study’ group. The randomisation was carried out by the researcher after patient consent was obtained."

Comment: not enough information on which to judge risk of bias

Allocation concealment (selection bias)Unclear risk

Quote: "Patients included in this study were randomised into their respective group by means of drawing a sealed envelope stating either ‘control’ group or ‘study’ group. The randomisation was carried out by the researcher after patient consent was obtained."

Comment: not enough information on which to base a judgement

Blinding (performance bias and detection bias)
All outcomes
Low risk

Quote: "As the intervention for the trial group was obvious to the researcher
and patients, compared with the no dressing control, blinding was impossible.

All discharged patients were routinely given a 2-week appointment to see their surgeon, who was blinded to the trial, for a wound assessment. On the 30th postoperative day, the ward staff nurses,who were also blinded to the trial, were given a CDC criteria checklist and phoned the patients to assess for SSI. Patients who were unable to describe their surgical site condition over the phone were asked to return to the clinic to have their surgical sites assessed by an advanced nurse practitioner, who was also blinded to the trial."

Comment: considered blinded outcome assessment for SSI (only outcome)

Incomplete outcome data (attrition bias)
All outcomes
Low riskFrom a figure in the paper it appears that 6 participants in total withdrew; 4 from Group A and 2 from Group B (for all dropouts reason given was medical complications unrelated to trial). We considered this to be a small number of withdrawals and of limited impact.
Selective reporting (reporting bias)Unclear riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasUnclear riskNo other biases noted.

Vogt 2007

Methods2-arm RCT undertaken in Denmark.
ParticipantsPeople undergoing elective vascular surgery
Interventions

Group A (n = 80): absorbent dressing (Mepore, Mölnlycke Health Care)
Group B (n = 80): hydrofibre/spun hydrocolloid dressing (Aquacel, ConvaTec)

All dressings were applied at the end of surgery, and remained in situ for 4 days. After 4 days, no dressing was applied if the wound was dry. In the few cases where a dressing was still needed, standard treatment was used (not described).

OutcomesPrimary review outcome: SSI (defined as signs of infection - redness, tenderness, swelling or exudate)
Secondary review outcomes: cost (cost/per participant including dressing, nurse time and other equipment, e.g. gloves),acceptability (participant assessment: composite outcome from discomfort at mobilisation, pain at dressing change, and skin problems. All combined onto 3-point scale where `good' = no discomfort at all; `moderate' = minor problems and `poor' = severe problems)
Notes

Trial outcome data: see Table 3

Follow-up: assessed daily for 4 days after surgery, at suture removal (typically at 14 days after surgery if in hospital), and at 6 weeks after surgery.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Before the study started a noninvolved person had mixed 160 notes, half of them marked Aquacel and half marked Mepore and put them in consecutive marked envelopes".
Allocation concealment (selection bias)Low risk"In the operating theatre the envelope was opened and the relevant dressing applied to the wound".
Blinding (performance bias and detection bias)
All outcomes
Unclear riskNo details provided in report on blinding for any outcome.
Incomplete outcome data (attrition bias)
All outcomes
High riskGroup A: 14 participants were not included (7 did not receive, or discontinued treatment, and 7 were lost to follow-up).
Group B: 10 participants were not included (5 did not receive, or discontinued treatment, and 5 were lost to follow-up).
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasLow riskNone noted

Wikblad 1995

Methods3-arm RCT undertaken in Sweden
ParticipantsPeople undergoing elective coronary bypass or valve-replacement surgery
InterventionsGroup A (n = 92): absorbent dressing (no further details provided)
Group B (n = 77): hydrocolloid dressing (DuoDerm, Convatec/Bristol-Myers Squibb)
Group C (n = 81): polyurethane matrix hydrocolloid dressing (Cutinova hydro, Beiersdorf AG)
Dressings changed if signs of leakage or exudate. All dressing removed on day 5 postoperatively.
Outcomes

Primary review outcome: SSI (definition of infection not given, although a culture was taken from the incision at day 5 postsurgery)

Secondary review outcomes: cost (days 1-5 per participant); pain (at day 5; rated on 3-point scale); ease of removal (dressing assessed by clinician as difficult to remove)

Notes

Trial outcome data: see Table 3

Follow-up: outcome data collected from days 1 to 5 postoperatively. Participants self-recorded information on wound appearance and feel 1 week after discharge, i.e. is wound red, does wound look swollen, is wound itchy? During fourth week after surgery 169 participants had the wound assessed by a nurse. Assessment included infection and treatment with antibiotics (yes/no).

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High risk

Quote: '... the secretary randomly selected a number from one to three (a number of each dressing type) and put the number on the anaesthesiologist's order sheet.'

Comment: deemed to be at high risk of bias

Allocation concealment (selection bias)High riskSee above
Blinding (performance bias and detection bias)
All outcomes
Unclear riskOn day 5, 2 independent reviewers assessed a photograph for redness, degree of wound healing and skin changes. Blinding not reported for infection.
Incomplete outcome data (attrition bias)
All outcomes
High riskLoss to follow-up: in the first week 34 dropped out (excessive bleeding = 15, reoperation = 7, postoperative complications = 1, died = 8, registration = 3). By the 4-week assessment a further 47 had been lost.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasLow riskNo other biases noted.

Wynne 2004

  1. a

    Abbreviations

    < = less than
    > = more than
    CDC = Centers for Disease Control and Prevention
    EQ-5D = EuroQol five dimensions questionnaire (a standardised instrument for measuring generic health status)
    GI = gastrointestinal
    ITT = intention-to-treat (analysis)
    n = number in group
    PHMB =
    PI = principal investigator
    RAND =
    RCT = randomised controlled trial
    SAS = statistical analysis system
    SSI = surgical site infection
    THR = total hip replacement
    TKR = total knee replacement
    VAS = visual analogue scale
    vs = versus

Methods3-arm RCT undertaken in Australia
Participants

People having cardiac surgery that required a median sternotomy incision

Exclusion criteria: immunosuppressed and non-consenting people, and those under the care of surgeons who were not participating in the study

InterventionsGroup A (n = 243): dry absorbent dressing (Primapore, Smith & Nephew) removed on day 2 postoperatively
Group B (n = 267): hydrocolloid dressing (DuoDerm Thin, ConvaTec) in situ for 5 days
Group C (n = 227): film dressing (Opsite, Smith & Nephew) in situ for 5 days
Outcomes

Primary review outcome: SSI (definition of infection based on CDC guidelines for prevention of surgical site infection. Infection defined as superficial (involving skin and subcutaneous tissues), or deep (involving muscle, bone and mediastinum), in conjunction with one of the following: excision of wound tissue, a positive wound culture or treatment with antibiotics)

Secondary review outcomes: cost (median per participant); acceptability (assessed by participants); ease of removal: (discomfort with removal - assessed by participants). Scarring and pain not reported.

Notes

Trial outcome data: see Table 3

Follow-up: outcome data collected daily on days 1-5 postoperatively. Subsequent follow-up via outpatient clinic, or phone call 4 weeks after discharge. At 4 weeks participants were questioned about their experiences with regard to pain, tenderness, redness, swelling, discharge or oozing from the chest wound; and whether they had sought medical attention or had antibiotic therapy initiated by doctor.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskQuote: "Patients were randomly assigned to one of the three treatments by the circulating nurse on the commencement of sternal skin closure".
Allocation concealment (selection bias)Unclear riskQuote: "Randomization was stratified equally across two operating theaters and was achieved using opaque envelopes".
Blinding (performance bias and detection bias)
All outcomes
High riskParticipants: not stated
Personnel: not stated
Outcome assessors: quote: "Blinding of data collectors to treatment was not feasible ...".
Incomplete outcome data (attrition bias)
All outcomes
Low riskSSI: denominator values suggested complete follow-up for short-term period.
Selective reporting (reporting bias)Low riskGiven the information presented in the paper, all prespecified outcomes reported.
Other biasUnclear riskVaried timings as well as dressing types.

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
  1. a

    Abbreviations

    RCT = randomised controlled trial
    TKA = total knee arthroplasty

Abejon 2012Not enough detail to confirm surgery type
Abejon 2013Not an RCT - quasi-randomised.
Ajao 1977Compared same dressing left in situ for different durations on surgical wounds healing by primary intention (timing trial).
Al-Belasy 2003Oral surgery
Allan 1996Not surgical wounds
Alsbjorn 1990Dressings applied to drain sites 1-2 days postoperatively
Anonymous 2013Unable to obtain abstract
Baker 1977Compared a plaster dressing that was placed over soft dressing material. No relevant outcomes reported.
Blondeel 2004Tissue-adhesive used as a wound closure method
Borgognoni 2000Data were only available from an abstract, and no further information could be obtained from author. Outcome was the recurrence of keloids and associated immunohistochemical investigations.
Borkar 2011Included children < 2 years of age
Boyce 1995Wounds healing by secondary intention
Brehant 2009Open wounds without planned healing (stoma)
Cabrales 2014Open not closed wounds
Choi 2005Unable to obtain study report
Chou 2010Not relating to skin closure (dura)
Chrintz 1989Not an RCT
Colom Majan 2002Study included scars and not open wounds.
Decaillet 1998All patients received 2 hours of pressure dressings postoperatively. Not clear whether evaluated dressings were applied before or after this.
Dell 2001Covered by a different Cochrane review group (Eyes and Vision)
Di Maggio 1994Not thought to have measured relevant outcomes
Dillon 2008Do not believe to be an RCT; no contact from author.
Dixon 2006The trial compared ointments applied to the wounds, and not dressings.
Dobbelaere 2015Not an RCT
Dosseh Ekoue 2008Compared same dressing left in situ for different durations on surgical wounds healing by primary intention (timing trial).
Edwards 1967Not an RCT. Groups were formed arbitrarily and not randomised.
Eymann 2010Participants < 2 years old
Fries 2014Open not closed wounds - confirmed after contact with author.
Furrer 1993Tissue-adhesive applied prior to wound closure thus not glue as dressing
Garne 1989Compared same dressing left in situ for different durations on surgical wounds healing by primary intention (timing trial).
Gbolahan 2015Surgery of the mouth and in children < 2 years old
Giri 2004Included some wounds that were infected at baseline
Gonzalez 2002Not an RCT
Grauhan 2010Quasi-randomised trial. Allocation of participants to the 2 study groups alternated according to the time of operation
Grover 2015Dressing/wound exposure was not the only systematic difference between the 2 arms. The exposure arm had daily applications of 5% povidone iodine solution that the dressing arm did not.
Guilbaud 1993Not surgical wounds
Guillotreau 1996Not surgical wounds
Gupta 1991Wounds healing by secondary intention
Heal 2009Compared same dressing left in situ for different durations on surgical wounds healing by primary intention (timing trial).
Hermans 2000Wounds healing by secondary intention
Hirose 2002Wounds healing by secondary intention
Hutchinson 1997Not surgical wounds
Igarza 1997Unable to obtain complete paper.
Johannesson 2008Vacuum dressing and no relevant outcome
Juergens 2011Wrong intervention
Kadar 2015Not an RCT
Kiefer 2016Not a wound dressing
Lambiris 1979Wrong intervention
Mandy 1985Not an RCT. 10 additional participants added to control group after initial randomisation.
Marinovic 2010Not sure if RCT or CCT - unable to confirm design.
Martin-Garcia 2005Not an RCT
Maw 1997Not an RCT
McVeigh 2011Not an RCT
Merei 2004Not an RCT, as participants were randomised by date of birth.
Meylan 2001Not an RCT.
Milne 1999Identification of blister formation
Moore 1997Wounds healing by secondary intention
Morales 2006Tissue-adhesive as a wound closure method
Müller 1993No relevant outcomes included
Nearuy 2000Wounds healing by secondary intention
Palao i Domenech 2008Mixture of wound types, mainly chronic (most common were leg ulcers)
Palao i Domenech 2009Unclear whether dressings applied to wounds in theatre.
Parvizi 2013Method of wound closure varied between groups, as glue was used in 1 arm
Pastorfide 1989Sprays and ointments used as comparisons, rather than dressings.
Piromchai 2008Compared a pressure dressing with a non-pressure dressing after thyroidectomy. Reported outcome was volume of fluid collected. Viewed as trial of applying pressure to wound rather than a dressing trial per se.
Pizarro Sule 2001Dressing was not only difference between trial arms
Ponnighaus 1999Study included wounds healing by secondary intention
Ravenscroft 2006No relevant outcomes measured. Whilst pain was assessed at dressing removal, there was no indication of how this was measured, or what the numbers 'meant'.
Reinicke 1990All participants operated on one day received the treatment and the following day received the control. Classed as quasi-randomised. Additionally, the study included data from contaminated wounds that were not randomised at all, but dressed according to surgeon's preference.
Ridley 2016Not an RCT
Robson 2012Topical treatment rather than dressing
Romero 2011Method of wound closure also varied between groups, as glue was used in 1 arm
Rosenfeldt 2003Unclear comparison group
Rushbrook 2014Not an RCT
Schwartz 2014Not thought to be an RCT - seems to use alternation. Not able to contact authors to confirm
Segers 2007The study included a range of types of wound to the hand including trauma and nail-bed injuries. Not all wounds were planned to heal by primary intention.
Shamiyeh 2001Tissue-adhesive used as a wound closure method
Sheppard 2014Conference abstract with limited data
Shima 1998Not an RCT
Signorini 2007The study treated keloid scars.
Singer 2002Tissue-adhesive used as a wound closure method
Sinha 2001Tissue-adhesive used as a wound closure method
Slawson 2002Tissue-adhesive used as a wound closure method
Sondergaard 1982The trial included participants with wounds that had already become infected postoperatively.
Stanirowski 2016aFollowing contact with the author, we did not consider this to be an RCT, due to use of alternation.
Stanirowski 2016bFollowing contact with the author, we did not consider this to be an RCT, due to use of alternation.
Staveski 2013Trial appears to include children < 2 years old (information from conference poster). Author contacted for confirmation. No reply received to date.
Staveski 2016Not correct study population.
Terrill 2000Not an RCT, since participants were allocated by year of birth.
Teshima 2009Not an RCT.
Tofuku 2012Not an RCT.
Torra i Bou 2013Reported clinical comparative evaluation. No mention of randomisation. Contacted author to confirm whether an RCT. No reply received to date.
Ubbink 2008Open wounds (not planned primary closure)
Valente 2008We do not believe this to be an RCT. Unable to contact author
Widgerow 2009Not an RCT.
Wipke-Tevis 1993Randomised to dressing 1 day postoperatively.
Wipke-Tevis 1998Both groups had the same dressing applied for 24 hours and were then randomised.
Yamanaka 2012Unable to obtain paper after several attempts
Yang 2013Wounds healing by secondary intention

Characteristics of studies awaiting assessment [ordered by study ID]

Goharshenasan 2016

MethodsRCT
Participants52 participants having bilateral symmetric incisions in randomly selected plastic surgical patients (split wound randomisation)
InterventionsHoney and standard dressing
OutcomesInfection
NotesWe think the honey was a topical treatment rather than dressing but require clarification from author

Siddiqui 2016

MethodsRCT
Participants144 participants (3-arm trial, 2 potentially relevant arms)
InterventionsAdvanced dressing compared with a different advanced dressing
OutcomesInfection
NotesUnclear what the type of dressings are used. We think it may be film versus another type of film, but require confirmation from authors.

Springer 2015

  1. a

    Abbreviations

    RCT = randomised controlled trial
    TKA = total knee arthroplasty

MethodsRCT
Participants143 participants having TKA
InterventionsOcclusive, antimicrobial surgical dressing or a standard surgical dressing
OutcomesUnclear
NotesNo relevant outcomes reported - contacted authors for more information on data collected

Characteristics of ongoing studies [ordered by study ID]

ISRCTN06792113

Trial name or titleHTA - 12/200/04: The Bluebelle study: FeasiBiLity stUdy of complEx, simple and aBsEnt wound dressings in eLective surgery
MethodsFeasibilty work includes small RCT
ParticipantsPeople with surgical wounds healing by primary intention
InterventionsSimple dressings, glue as dressing and no dressing
OutcomesSSI
Starting dateJune 2014
Contact information Professor Jane Blazeby
Noteswww.nets.nihr.ac.uk/projects/hta/1220004

NCT02619773

Trial name or title

The use of mupirocin dressings and its effect on surgical site infections in elective colorectal

surgery: a prospective, randomised controlled trial

MethodsRCT
ParticipantsSurgical patients
InterventionsMupirocin dressing compared with island dressing
OutcomesSSI
Starting dateNovember 2015
Contact informationStephen B Shapiro, MD
Notes 

NCT02771015

Trial name or titleClinical trial to evaluate the performance of a flexible self-adherent absorbent dressing coated with a soft silicone layer compared with a standard wound dressing after orthopedic or spinal surgery: study protocol for a randomised controlled trial
MethodsRCT
Participants200 participants undergoing orthopedic or spinal surgery
InterventionsMepilex Border Post-Op versus a standard dressing (Cosmopor E adhesive)
OutcomesBlistering incidence; pain
Starting dateSeptember 2015
Contact informationDepartment of Orthopedics and Trauma Surgery, University Hospital of Cologne, Kerpener Str. 62, Cologne D - 50924, Germany
NotesOngoing

NCT02904200

  1. a

    Abbreviations

    RCT = randomised controlled trial
    SSI = surgical site infection

Trial name or titleA prospective, randomised, controlled clinical investigation, comparing trauma to peri-wound skin and pain when using two different wound dressings
MethodsRCT
ParticipantsVascular surgery patient - not clear from database
InterventionsSilicon dressing compared with acrylic dressing
OutcomesSkin condition. Unclear if SSI will be assessed
Starting dateSeptember 2016
Contact information tina.kjellen@molnlycke.com
NotesContacted company for more information

Ancillary