Scolaris Content Display Scolaris Content Display

Base de datos Cochrane de Revisiones Sistemáticas Protocolo - Intervención

Mesh fixation techniques for laparoscopic inguinal hernia repair in adults

Declaraciones de intereses de los autores

Versión publicada: 02 octubre 2017 Historial de versiones

https://doi.org/10.1002/14651858.CD008954.pub2
Contraer todo Desplegar todo

Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects of different methods of mesh fixation and techniques for laparoscopic inguinal hernia repair in adults. The specific comparisons of interest are as follows:

  • mesh fixation compared with no mesh fixation;

  • non‐mechanical fixation techniques compared with mechanical fixation techniques;

  • techniques for peritoneal closure in TAPP hernia repair.

Background

Description of the condition

An inguinal hernia is a protrusion of a sac of peritoneum (often containing intestine or other abdominal contents) through a weakness in the abdominal wall in the groin. It usually presents as a lump, with or without some discomfort that may limit daily activities and the ability to work. Around 98% of inguinal hernias are found in men because of the vulnerability of the male anatomy to the formation of hernias in this area of the body. Inguinal hernias can occasionally be life‐threatening if the bowel within the peritoneal sac strangulates or becomes obstructed, or both. Inguinal hernia repair is one of the most commonly performed general surgical operations. In England, there were approximately 70,000 surgical repairs of inguinal hernias in 2001/2002, affecting 0.14% of the population and utilising over 100,000 National Health Service bed‐days of hospital resources (McCormack 2005).
An inguinal hernia is repaired by placing or suturing a prosthetic mesh in one of the layers of the abdominal wall to cover the weakness; this can be performed either by open surgery or by a minimal access key‐hole (laparoscopic) approach (Schultz 1990). Laparoscopic repair, which involves performing surgery through small incisions, is associated with less postoperative pain and a more speedy return to normal activities of daily life (McCormack 2003; Wauschkuhn 2010). Such repairs can be performed via total extraperitoneal (TEP) or transabdominal preperitoneal (TAPP) methods. In TAPP the surgeon enters the peritoneal cavity and places a mesh through a peritoneal incision. TEP is different in that the peritoneal cavity is not entered, but the mesh is positioned at the same place; behind the muscles of the abdominal wall and in front if the peritoneum. Although most laparoscopic inguinal hernia repairs are now performed as day‐case procedures and have a very satisfactory outcome, morbidity in the form of chronic groin pain and hernia recurrence continues to be a significant problem. The overall incidence of moderate‐to‐severe post operative chronic pain is 10% to 12% (Poobalan 2003; Aasvang 2005; Nienhuijs 2007), and may significantly affect a person's quality of life. The incidence of recurrence after laparoscopic hernia repair has been reported to be 2.5% (McCormack 2003).

Description of the intervention

During the repair of an inguinal hernia, sutures or tacks are generally used to secure the prosthetic mesh in place. In TAPP repairs the peritoneum is closed using sutures or tacks. These mesh fixation or peritoneal closure techniques may contribute to postoperative chronic pain presumably due to nerve irritation or entrapment (Heise 1998). Intraoperative strategies to reduce pain include the non‐fixation of mesh or the use of non‐mechanical methods of mesh fixation other than tacking or suturing, which may be less traumatic to the local tissue and less likely to cause local nerve entrapment. These non‐mechanical methods include self‐fixating meshes or glue. Similarly, closing the peritoneum with sutures may be less traumatic than the use of tacks, thus resulting in less postoperative pain (Ross 2015).  

How the intervention might work

Two types of glue, fibrin glue and N‐butyl‐2‐cyanoacrylate, are the most commonly used glues for mesh fixation. Fibrin glue is a biodegradable adhesive that combines human‐derived fibrinogen and thrombin. In addition to its haemostatic action, the fibrinogen component gives the product tensile strength and adhesive properties. N‐butyl‐2‐cyanoacrylate is a new generation of cyanoacrylate that has been used as a surgical tissue adhesive since the 1960s. Self‐fixating mesh has a large number (>5000) of microgrips that help secure the mesh to tissue without the need for tacks or sutures. When the mesh is placed in between layers of the abdomen it is kept in place by intra‐abdominal pressure (the rationale behind non‐fixation of the mesh) (Campanelli 2016).

Why it is important to do this review

A number of randomised controlled trials (RCTs) have investigated the merits of different types of mesh fixation, and have compared mechanical mesh fixation (sutures, tacks) versus non‐mechanical fixation (self fixating mesh, glue), as well as fixation versus non fixation (Cristaudo 2015; Hoyuela 2017) .To date, however, a consensus opinion regarding which method is most advantageous has not been reached. Similary, there is no consensus on the optimal technique for peritoneal closure in TAPP repair. At present, therefore, the choice of mesh fixation and peritoneal closure method depends on the individual surgeon's practice.

The aim of this systematic review is to determine whether there is any difference in outcomes and morbidity when mesh is fixed or not during laparoscopic inguinal hernia repair. We will also compare different methods of mesh fixation (i.e. self‐fixation, glue sealant, tacks (non‐absorbable and absorbable), and sutures) and techniques of peritoneal closure in TAPP repairs (tacks/sutures). As outcomes may also be affected by a number of underlying factors, including hernia size, primary or recurrent presentation as well as laterality (unilateral versus bilateral), will intend to assess the role these effect modifiers.

Any evidence of benefits in terms of reduced postoperative pain with no increase in recurrence associated with different methods of mesh fixation/non‐fixation or peritoneal closure techniques could therefore have a significant impact on clinical practice.

Objectives

To assess the effects of different methods of mesh fixation and techniques for laparoscopic inguinal hernia repair in adults. The specific comparisons of interest are as follows:

  • mesh fixation compared with no mesh fixation;

  • non‐mechanical fixation techniques compared with mechanical fixation techniques;

  • techniques for peritoneal closure in TAPP hernia repair.

Methods

Criteria for considering studies for this review

Types of studies

We will consider all RCTs comparing no mesh fixation with fixation, or comparing different methods of mesh fixation during laparoscopic inguinal hernia repair, via either the TEP or TAPP approaches, in adults. We will include trials irrespective of the number of participants randomised. We will include trials with multiple treatment arms provided they randomise participants to at least two arms of laparoscopic hernia repair and compare at least one intervention of interest.

Types of participants

Adults (aged 18 years old and over) undergoing laparoscopic inguinal hernia repair with mesh placement for a primary inguinal hernia. Younger individuals with an inguinal hernia are generally treated without mesh and we will thus exclude them from the study.

Types of interventions

1. Laparoscopic inguinal hernia repair using:

  • mesh fixation (mechanical or non‐mechanical) compared with no mesh fixation;

  • non‐mechanical fixation techniques (glue, self‐fixating mesh) compared with mechanical fixation techniques (absorbable tacks, non‐absorbable tacks, staples, sutures).

2. Techniques for peritoneal closure in TAPP hernia repair (suture closure compared with closure using tacks or staples).

Types of outcome measures

Primary outcomes

  1. Hernia recurrence (clinical or radiological at any time point)

  2. Chronic pain: pain persisting beyond three months postoperatively (categorical outcome: yes/no) (IASP 1986)

  3. Persisting numbness: numbness in the groin or testicle persisting beyond three months postoperatively

Secondary outcomes

  1. Length of surgery (in minutes)

  2. Immediate postoperative pain (visual analogue scale (VAS)/pain score)

  3. Vascular/visceral injury at operation

  4. Haematoma/seroma development in postoperative period

  5. Length of hospital stay (in days)

  6. Urinary retention in immediate postoperative period

  7. Wound infection/mesh infection at any time point

  8. Recovery time to normal activity (in days)

Search methods for identification of studies

Electronic searches

We will conduct a comprehensive literature search to identify all published and unpublished RCTs, imposing no language or year of publication restrictions. We will search the following electronic databases:

  • Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (Appendix 1);

  • MEDLINE (1950 to present) (Appendix 2);

  • Embase (1974 to present) (Appendix 3);

  • LILACS (1982 to present) (Appendix 4);

  • Turning Research into Practice (TRIP) database.

In addition to these databases, the following trial registers will be sought for ongoing studies:

Searching other resources

We will handsearch the reference lists of all identified articles to identify other potential studies eligible for inclusion. These will include well‐conducted systematic reviews and meta‐analyses. We will exclude conference abstracts, case reports and case series.

Data collection and analysis

Selection of studies

Two authors (AG and NS) will independently examine trials to determine whether they should be included according to the specified inclusion criteria. We will resolve disagreements by consulting a third review author (FM). We will present reasons for the inclusion and exclusion of each study in 'Characteristics of included studies' and 'Characteristics of excluded studies' tables, respectively. We will also present a PRISMA flow chart to visually show the selection and exclusion of studies, specifying the number of studies considered at each step. We will include studies reporting results in abstract form only in the 'Studies awaiting assessment' section and we will list ongoing studies in 'Characteristics of ongoing studies' tables.

Data extraction and management

We will develop a data extraction form into which two authors (AG and NS) will independently extract the following data.

  1. Participant characteristics: age, sex, employment (where documented), body mass index (where documented);

  2. Total number of participants originally assigned to each intervention group;

  3. Intervention: mesh fixation technique, if used;

  4. Details of hernia repair: primary/recurrent, unilateral/bilateral and TEP/TAPP, and peritoneal closure technique used in TAPP;

  5. Length of follow‐up;

  6. Outcomes: length of operation, vascular/visceral injury, length of hospital stay, haematoma/seroma development, postoperative analgesic requirements/postoperative pain score, wound/mesh infection, urinary retention, duration before return to usual activities of daily life, recurrence, chronic pain, persistent numbness.

We will check the data for accuracy before entering them into Review Manager (RevMan 2014) for data analysis. We will resolve any disagreements by consulting a third review author (FM).

Assessment of risk of bias in included studies

Two review authors (AG and NS) will assess the methodological quality of the included trials; any disagreements will be resolved by consulting a third review author (FM or SB). We will use the Cochrane 'Risk of bias' tool to assess the risk of bias in included trials (Chapter 8 in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011)). We will assess the following domains:

  • random sequence generation;

  • allocation concealment;

  • blinding of participants and personnel (although blinding of surgeons may not be possible for some of the interventions of interest making the included studies amenable to a high risk of bias in this domain);

  • blinding of outcome assessment for both objective and subjective outcomes;

  • incomplete outcome data;

  • selective reporting bias;

  • other sources of bias (imbalance in baseline characteristics, technique used to establish recurrence ‐ whether clinical or radiological, surgery conducted by a single surgeon or multiple surgeons, or whether study is multicentric).

Bias is an over‐ or underestimation of the actual intervention effect that is introduced by limitations in study design, conduction and analysis. We will judge each domain to be at low risk, high risk or unclear risk of bias for each included trial according to criteria used in the Cochrane 'Risk of bias' tool (see Appendix 5) (Chapter 8.5.d in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011)).

Measures of treatment effect

We will analyse data using RevMan 2014, following recommendations in the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). We will express dichotomous outcomes as risk ratios (RR) with 95% confidence intervals (CIs), and continuous outcomes as mean differences (MD) with 95% CIs where the data are assessed using the same measure and standardised mean differences (SMD) with 95% CIs where the same outcomes are assessed using different measures (such as different chronic pain scales).

Unit of analysis issues

For participants with bilateral hernias we will base the analysis on whether randomisation was carried out by participant or by hernia.

  • Where randomisation was by participant, and where participants received the same intervention on both hernias, we will use the number of participants as the denominator in the analysis. However, if outcomes are reported separately for the individual hernias we will then use the number of hernias in the analysis.

  • Because bilateral hernias may receive different interventions, if randomisation was by hernia, we will make a separate outcome judgement for each hernia using the number of hernias as the denominator in the analysis.

Dealing with missing data

We will analyse missing data according to the intention‐to‐treat principle and perform a sensitivity analysis substituting missing values with those from the best (missing participants did not suffer an event) and worst (missing participants did suffer an event) scenarios to test the influence of missing data on the robustness of effect estimates. We will also contact the corresponding authors of the included trials for missing information, including missing statistics, or missing information regarding the 'Risk of bias' assessment.

Assessment of heterogeneity

We will assess clinical heterogeneity between the studies, focusing on participants, type of intervention and measurement of outcomes. We will determine methodological heterogeneity by assessing variabilities in the study design and risk of bias. We will assess statistical heterogeneity using the Chi2 statistic, with the level of statistical significance set at 0.10, and the I2 statistic to quantify inconsistency across the studies. We will interpret the value of the I2 statistic according to the recommendations provided in the Cochrane Handbook for Systematic Reviews of Interventions (Chapter 9 (Deeks 2011)): 0% to 40% is likely to indicate minimal heterogeneity, 30% to 60% may represent moderate heterogeneity, 60% to 90% may represent substantial heterogeneity, and 90% to 100% may represent considerably significant heterogeneity.

Assessment of reporting biases

We will perform and present funnel plots if more than 10 studies are included by plotting intervention effects on a logarithmic scale against the standard error on the y‐axis (Sterne 2011). We will supplement these with Egger's linear regression test if we identify a sufficiently large number of studies (Egger 1997). We will also investigate the presence of publication bias by searching for the protocols of included trials to assess whether trials report all planned outcomes (selective reporting bias).

Data synthesis

For dichotomous outcomes, we will pool data in meta‐analyses using the Mantel‐Haenszel approach, and for continuous outcomes, we will use the inverse variance method. The final choice of model used will depend upon the number of studies included in final analysis. If the number of studies included in the final analysis is less than 5, we will use a fixed‐effect model; hence, data from all included studies, irrespective of level of heterogeneity, will be pooled for the same reason. However, if the number of studies is more than 5 then we will use a random‐effects model to adjust for any variation.

Subgroup analysis and investigation of heterogeneity

Where possible, we will perform the following subgroup analyses using a formal test for subgroup differences:

  • unilateral versus bilateral hernias;

  • primary versus recurrent hernias;

  • hernia size (if sufficient data are available).

Sensitivity analysis

Where possible, we will perform the following sensitivity analyses to test the robustness of results:

  1. excluding unpublished studies (if any);

  2. excluding studies with overall high risk of bias;

  3. replacing missing data with values from the best (missing participants did not suffer an event) and the worst case (missing participants did suffer an event) scenarios.

We may perform further sensitivity analyses if potential issues are identified during the course of the review. We will perform sensitivity analyses for all outcomes.

Summary of findings

We will assess the quality of the evidence for all outcomes using the GRADE approach, as provided in the Cochrane Handbook for Systematic Reviews of Interventions (Chapter 12), and present this as 'Summary of findings' tables (Schünemann 2011). These tables present key information concerning the quality of the evidence, the magnitude of effects of the interventions examined and the sum of the available data for all outcomes. We will construct and present tables for the following outcomes:

  • hernia recurrence;

  • chronic pain;

  • persisting numbness;

  • immediate postoperative pain;

  • haematoma/seroma development in postoperative period;

  • length of hospital stay;

  • recovery time to normal activity.

The GRADE system classifies the quality of evidence into one of four grades:

  1. High: Further research is very unlikely to change our confidence in the estimate of effect;

  2. Moderate: Further research is likely to have an impact on our confidence in the estimate of effect an may change the estimate;

  3. Low: Further research is very likely to have an important impact on our confidence on the estimate of effect and is likely to change the estimate;

  4. Very low: Any estimate of effect is very uncertain.

The quality of evidence can be downgraded by one (serious concern) or two levels (very serious concern) for the following reasons: risk of bias, inconsistency (unexplained heterogeneity, inconsistency of results), indirectness (indirect population, intervention, control, outcomes), imprecision (wide CIs) and publication bias. Two authors (NS and SB) will independently assess the quality of evidence based on GRADE classification. We will resolve any disagreements by discussion.