Bed rest for pressure ulcer healing in wheelchair users

Zena EH Moore; Menno T van Etten; Jo C Dumville

doi:10.1002/14651858.CD011999.pub2

Reposo en cama para la cicatrización de la úlcera por presión en los usuarios de sillas de ruedas

Declaraciones de intereses de los autores

Versión publicada: 17 octubre 2016 Historial de versiones

https://doi.org/10.1002/14651858.CD011999.pub2

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Resumen

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Antecedentes

Las úlceras de decúbito, que son lesiones localizadas en la piel o el tejido subyacente, o ambos, ocurren cuando los pacientes no son capaces de cambiar de posición para aliviar la presión sobre las prominencias óseas. Las úlceras de decúbito suelen ser dolorosas y difíciles de cicatrizar, e impactan de forma negativa sobre la calidad de vida del paciente. Las guías internacionales indican el reposo en cama como un componente de la estrategia terapéutica para el tratamiento de las úlceras por presión en los usuarios de sillas de ruedas. Los posibles riesgos y beneficios necesitan ser considerados cuando se evalúa la efectividad del reposo en cama como una intervención para el tratamiento de las úlceras por presión en esta población. Por lo tanto, fue importante buscar y evaluar las pruebas de estudios de investigación existentes para determinar la repercusión del reposo en cama en la cicatrización de las úlceras por presión en los usuarios de sillas de ruedas.

Objetivos

Evaluar la repercusión del reposo en cama en la cicatrización de la úlcera por presión, en los usuarios de sillas de ruedas, de cualquier edad, que residen o son atendidos en cualquier ámbito.

Métodos de búsqueda

En octubre 2016, se hicieron búsquedas en: registro especializado del Grupo Cochrane de Heridas (Cochrane Wounds Group); Registro Cochrane Central de Ensayos Controlados (Cochrane Central Register of Controlled Trials) (CENTRAL) (The Cochrane Library); Ovid MEDLINE (incluyendo In‐Process & Other Non‐Indexed Citations, MEDLINE Daily y Epub Ahead of Print); Ovid EMBASE y EBSCO CINAHL Plus. También se realizaron búsquedas de estudios en curso y no publicados en registros de ensayos clínicos y actas de congresos. No hubo restricciones con respecto al idioma, la fecha de publicación ni el ámbito del estudio.

Criterios de selección

Se consideraron los ensayos controlados aleatorios (ECA) y ECA en grupos que se evaluaran la repercusión del reposo en cama para la cicatrización de las úlceras por presión en los usuarios de sillas de ruedas.

Obtención y análisis de los datos

Dos autores de la revisión evaluaron de forma independiente la elegibilidad de los títulos y resúmenes de los estudios identificados mediante la estrategia de búsqueda.

Resultados principales

No se identificaron estudios que cumplieran los criterios de inclusión.

Conclusiones de los autores

Se planificó evaluar las pruebas derivadas de estudios de investigación, de los ensayos controlados aleatorios, de la repercusión del reposo en cama en la cicatrización de la úlcera por presión en los usuarios de sillas de ruedas. Ningún estudio cumplió los criterios de inclusión. No puede precisarse si el reposo en cama logra un cambio en la cicatrización de las úlceras por presión en los usuarios de sillas de ruedas. Se necesitan ensayos bien diseñados que aborden resultados clínicos, de calidad de vida y económicos importantes.

PICO

Population

Intervention

Comparison

Outcome

El uso y la enseñanza del modelo PICO están muy extendidos en el ámbito de la atención sanitaria basada en la evidencia para formular preguntas y estrategias de búsqueda y para caracterizar estudios o metanálisis clínicos. PICO son las siglas en inglés de cuatro posibles componentes de una pregunta de investigación: paciente, población o problema; intervención; comparación; desenlace (outcome).

Para saber más sobre el uso del modelo PICO, puede consultar el Manual Cochrane.

Resumen en términos sencillos

disponible en

Reposo en cama para el tratamiento de las úlceras de decúbito (úlceras por presión) en los usuarios de sillas de ruedas

Antecedentes

Las úlceras de decúbito (también conocidas como úlceras por presión) son heridas que se producen en la piel o los tejidos subyacentes como resultado de la presión no aliviada sobre los puntos óseos que soportan peso del cuerpo, como la cadera, el talón o la región lumbar. Los pacientes en riesgo son aquellos con movilidad reducida. Por tanto, los usuarios de sillas de ruedas están en riesgo porque permanecen sentados durante períodos prolongados. Las úlceras de decúbito pueden ser difíciles de curar y son propensas a la infección y otras complicaciones. Cuando estas heridas se producen en los usuarios de sillas de ruedas, el reposo en cama se considera una importante medida para aliviar la presión sobre la parte del cuerpo que soporta peso en la posición de sentado. Se piensa que este cambio de una posición de sentado a acostado mejora la cicatrización de la herida.

Pregunta de la revisión

Se pretendía explorar la repercusión del reposo en cama en la cicatrización de las úlceras por presión en los pacientes que utilizan una silla de ruedas. Los estudios aptos podían incluir a los usuarios de sillas de ruedas de cualquier edad con una úlcera por presión en cualquier ámbito (hospital, residencial, el propio domicilio del paciente, etc.).

Datos encontrados

En octubre de 2016 se realizaron búsquedas exhaustivas en la bibliografía médica de ensayos controlados aleatorios que compararan el reposo en cama con ningún reposo en cama para la cicatrización de las úlceras por presión en los usuarios de sillas de ruedas. No se encontró ningún ensayo que se hubiera realizado en esta área. De allí que no se pueda precisar si el reposo en cama mejora la cicatrización de las úlceras por presión en los usuarios de sillas de ruedas, o cuáles podrían ser los efectos beneficiosos y perjudiciales de este tratamiento. Se necesitan ensayos que comparen la cicatrización de la úlcera por presión con y sin reposo en cama en los usuarios de sillas de ruedas.

Este resumen en términos sencillos está actualizado hasta octubre 2016.

Authors' conclusions

Implications for practice

Pressure ulcers are common, costly and impact negatively on the individual's quality of life. Bed rest for the treatment of pressure ulcers in wheelchair users is often advocated; however, there is no evidence from randomised controlled trials to support or refute the use of bed rest for this purpose. Despite this, international guidelines in the field of pressure ulcer prevention recommend the use of a bed rest for treating pressure ulcers (NPUAP 2014). Additional research is needed to demonstrate the effect bed rest on pressure ulcer healing among wheelchair users.

Implications for research

There are no trials that have explored the use of bed rest for pressure ulcer healing in wheelchair users, despite its recommendation within international pressure ulcer prevention and management guidelines (NPUAP 2014). Future trials to answer this question are justified, based on the incidence of pressure ulcers and their consequences in wheelchair users. Future trials should be large enough to show meaningful differences; include participant‐related outcomes such as acceptability, adverse events and quality of life; and economic evaluations to assist healthcare managers to make rational decisions. Standard, validated tools should be used to measure outcomes such as pressure ulcer staging and quality of life.

Background

Description of the condition

A pressure ulcer is defined as a "localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in combination with shear. A number of contributing or confounding factors are also associated with pressure ulcers; the primary of which is impaired mobility" (NPUAP 2014). Pressure is the amount of force acting on a unit of area (O'Callaghan 2007). Shear forces occur in soft tissue when these tissues are stretched, which happens when the bony structures move but the skin is stationary (Sanders 2005). Pressure ulcers commonly occur in individuals who have reduced activity and/or mobility and so are exposed to prolonged periods of exposure to sustained pressure/shear forces (Gefen 2008). Elderly with reduced activity/mobility, people with spinal cord injury and those who are sedated following trauma or surgery are at increased risk of pressure ulcer development (Moore 2011; Moore 2014), however, potentially any person of any age could develop a pressure ulcer if he/she were exposed to the causative factors, that is, sustained unrelieved pressure and shear (McLane 2004).

Pressure ulcers vary in severity. One of the most widely recognised systems for categorising pressure ulcers is the National Pressure Ulcer Advisory Panel system, which is summarised below (NPUAP 2014).

Category/Stage I ‐ non‐blanchable erythema: "Intact skin with non‐blanchable redness of a localized area usually over a bony prominence. Darkly pigmented skin may not have visible blanching; its colour may differ from the surrounding area. The area may be painful, firm, soft, warmer or cooler as compared to adjacent tissue. Category I may be difficult to detect in individuals with dark skin tones. May indicate "at risk" persons."

Category/Stage II ‐ partial thickness: "Partial thickness loss of dermis presenting as a shallow open ulcer with a red pink wound bed, without slough [dead tissue]. May also present as an intact or open/ruptured serum‐filled or sero‐sanguinous [serum and blood] filled blister. Presents as a shiny or dry shallow ulcer without slough or bruising [bruising indicates deep tissue injury]. This category should not be used to describe skin tears, tape burns, incontinence associated dermatitis, maceration [damage through the skin being wet] or excoriation [damage through scratching/abrasion or burns]."

Category/Stage III ‐ full thickness skin loss: "Full thickness tissue loss. Subcutaneous fat may be visible but bone, tendon or muscle are not exposed. Slough may be present but does not obscure the depth of tissue loss. May include undermining and tunnelling. The depth of a Category/Stage III pressure ulcer varies by anatomical location. The bridge of the nose, ear, occiput [back of the head] and malleolus [ankle] do not have [adipose] subcutaneous tissue and Category/Stage III ulcers can be shallow. In contrast, areas of significant adiposity can develop extremely deep Category/Stage III pressure ulcers. Bone/tendon is not visible or directly palpable."

Category/Stage IV ‐ full thickness tissue loss: "Full thickness tissue loss with exposed bone, tendon or muscle. Slough or eschar [scabbing] may be present. Often includes undermining and tunnelling. The depth of a Category/Stage IV pressure ulcer varies by anatomical location. The bridge of the nose, ear, occiput and malleolus do not have [adipose] subcutaneous tissue and these ulcers can be shallow. Category/Stage IV ulcers can extend into muscle and/or supporting structures (e.g. fascia, tendon or joint capsule) making osteomyelitis [bone infection] or osteitis [inflammation of bone] likely to occur. Exposed bone/muscle is visible or directly palpable."

The World Health Organization suggests that the wheelchair is one of the most commonly used assistive devices for enhancing personal mobility (WHO 2010). It is estimated that 10% of the global population ‐ almost 650 million people ‐ have disabilities and 10% of these individuals require the use of a wheelchair (WHO 2010). When a person is seated, body weight is loaded onto a relatively small surface area, namely the ischial tuberosities (the sitting bones), the buttocks, coccyx and upper thighs (Stockton 2002). When sitting the weight of the individual is forced against the supporting seat surface which compresses the soft tissues and increases the risk of pressure ulceration. Regular repositioning, every 15 to 30 minutes, is recommended for people confined to wheelchairs (Schofield 2013). However, protracted periods of time spent without relieving pressure on the weight bearing areas is a common problem for wheelchair users. In one study of community‐dwelling wheelchair users the most frequently reported continuous sitting time was 12 hours (Stockton 2002). A further study identified that the majority of individuals confined to wheelchairs did not adhere to recommended repositioning practices, even when they had the ability to reposition themselves independently (Schofield 2013).

Stockton 2002 identified a point prevalence of pressure ulcers of 58% (stage I and above) among 136 community‐dwelling wheelchair users in the UK. Another study, among 50 people with acute spinal cord injury, found a prevalence of 37% (stage I and above) (Sheerin 2011). In another study undertaken between 1986 and 2002, 27% of 3361 people with spinal cord injury had one or more episodes of pressure ulcers of stage II or above (Chen 2005). Furthermore, the prevalence of pressure ulcers significantly increased with time post injury (11.5% at year 1 rising to 21% at year 15; Chen 2005). More recently, Lala 2014 reported that 33.5% of a cohort of 1137 people with spinal cord injury developed a pressure ulcer within the first year of injury. Brienza 2010 identified an incidence of 17.6% ‐ specifically referred to as sitting pressure ulcers ‐ among elderly wheelchair users cared for within a nursing home setting, occurring over the ischial tuberosities or the sacral/coccyx region (stage I or above). In Africa, a study conducted at the National Spinal Injury Hospital Kenya noted a pressure ulcer prevalence of 68% (Nangole 2009), while in a study in Thailand among wheelchair users with chronic spinal cord injuries, pressure ulcer prevalence was 26.4% (Kovindha 2015). An overall incidence of 39.2% was identified among 5995 people with spinal cord injury in Iran (Tagipoor 2009), and in Brazil 47 people within the same population showed an overall incidence of 42.5% (Nogueira 2006).

Pressure ulcers have a large impact on those affected; the ulcers can be painful, and may become seriously infected or malodorous. It has been shown that after adjustment for age, sex and co‐morbidities, people with pressure ulcers have a lower health‐related quality of life than those without pressure ulcers (Spilsbury 2007; Essex 2009). More specifically, when people with both spinal cord injury and pressure ulcers are compared with similar people without pressure ulcers, those with pressure ulcers had significantly lower scores (worse health status) on all SF‐36 sub scales (Lourenco 2014). The number of pressure ulcers also influences the individual's health‐related quality of life; for example in one study in Canada, 10% of people with one or two pressure ulcers and 16% of individuals with three or more pressure ulcers reported their quality of life as being 'very bad' or 'bad' compared with only 6.9% of individuals without pressure ulcers (Lala 2014).

In an economically constrained health service, revenue spent on pressure ulcers is a concern, as it is suggested that many pressure ulcers can be avoided with appropriate risk assessment and use of interventions targeted at combating this risk (Moore 2014). However, despite this premise, it is estimated, in the UK, that approximately 4% of the annual healthcare budget is being spent on pressure ulcers, with nursing time accounting for 41% of these costs (Posnett 2009). Pressure ulcers have been shown to increase length of hospital stay, readmission and mortality rates (Lyder 2012), and add considerably to the cost of an episode of hospital care (Chan 2013). Figures from the USA suggest that in 2006 half a million hospital stays noted 'pressure ulcer' as a diagnosis; for adults, the total hospital costs of these stays was USD 11 billion (Russo 2008). Costs to the Australian healthcare system for treating pressure ulcers have been estimated at AUD 285 million per annum (Graves 2005). Specifically, for those with a spinal cord injury coupled with a pressure ulcer cared for within a community care setting in Canada, the added cost is approximately CAD 4800 a month or almost CAD 57,000 annually (Chan 2013).

Description of the intervention

The 2014 pressure ulcer prevention and management guidelines recommend periods of bed rest to promote ulcer healing if a pressure ulcer is located on area of the body that bears weight during sitting, such as the ischial or sacral area (NPUAP 2014). This involves confining the individual to bed for varying periods of time, and restricting his/her normal activities either partially or completely. This can be devastating for the person, whose participation in usual daily activities will be restricted if he/she is unable to spend a normal amount of time sitting (Norton 2004). However, sometimes the use of bed rest as part of the management plan is seen as unavoidable due to the extensive nature of these pressure ulcers.

How the intervention might work

Wound healing is a normal response to injury. It is initiated after the skin's integrity has been interrupted, for example, by the development of a pressure ulcer (Martin 1997). The purpose of the healing process is to replace the tissue that has been damaged with living tissue, and to restore the continuity of the skin (Tarnuzzer 1996). Open wounds, including pressure ulcers, heal through formation of granulation tissue and epithelialisation (Slavin 1996). Granulation tissue is characterised by a high density of blood vessels, capillaries and many different types of cells, so the metabolic need of the wounded area is great (Krishnamoorthy 2001). Normal cellular metabolism requires an adequate supply of oxygen and nutrients, and also an effective elimination of waste metabolites (Tarnuzzer 1996). Pressure and shear cause cell deformation, impede normal osmosis and diffusion, and alter tissue perfusion (the process through which a body delivers blood to capillary beds). Therefore when an individual actually develops a pressure ulcer he/she should not bear weight on the affected area, as perfusion is central to cell repair (Tarnuzzer 1996). This is why bed rest is thought to be advantageous, in that it allows for the individual to offload pressure/shear from the affected area, and so increase perfusion of the wound bed with the aim of enhancing wound healing potential in that area.

It is important to note that there might also be other adverse issues associated with bed rest ‐ it can represent a large lifestyle change for patients and may have a psychological impact. Long periods of bed rest may increase the risk of chest infections, as well as cause muscular degeneration, which can require a long recovery period (Norton 2004). Bed rest can also cause what is known as deconditioning of the body (Stuempfle 2007); deconditioning is defined as the loss of muscle tone and endurance due to chronic disease, immobility, or loss of function and is thought to affect all of the organs of the body. This is caused by a number of mechanisms, including a reduced hydrostatic pressure gradient within the cardiovascular system, unloading of forces on skeletal muscles and bones, and reduced total energy expenditure (Stuempfle 2007). Bed rest has a negative economic impact on the person and his/her dependents due to making work impossible. This inability to work can result in a loss of the work habit, and reduce the likelihood of the person eventually returning to work (Andersson 1989). Therefore, the potential benefits and risks need to be considered when assessing the effectiveness of bed rest as an intervention for treating pressure ulcers in wheelchair users.

Why it is important to do this review

Pressure ulcers commonly occur amongst wheelchair users, therefore identification of strategies which reduce recovery time is important (Moore 2014). Bed rest may or may not be an effective treatment for pressure ulcers in wheelchair users; the balance of benefits and risks associated with bed rest must be assessed systematically. Although there have been many reports of bed rest as a modality for pressure ulcer management, many of these reports appear to have been underpinned by anecdotal evidence, or have been subjected to little critical scrutiny (NPUAP 2014), so overall, the precise impact of bed rest is unclear. Therefore, it was important to search and appraise the literature systematically in order to determine the impact of bed rest on the management of pressure ulcers in wheelchair users.

Objectives

To assess the impact of bed rest on pressure ulcer healing in wheelchair users, of any age, who are living or being cared for in any setting.

Methods

Criteria for considering studies for this review

Types of studies

Published and unpublished randomised controlled trials (RCTs), including cluster‐RCTs were eligible for inclusion, irrespective of language of report. Cross‐over trials were eligible if outcome data were available from the end of the first treatment period prior to cross‐over. Studies using quasi‐randomisation were to be excluded.

Types of participants

People of any age, in any setting (hospitals, nursing homes, residential care, rehabilitation centres, living at home) who are wheelchair users and have an existing pressure ulcer (of any stage), were eligible for inclusion.

Types of interventions

The intervention of interest was bed rest (as defined by study authors, but should have involved a period of non‐seated time, so may have included complete bed rest or periodic bed rest, or both) used for the treatment of pressure ulcers in wheelchair users. The comparison was to be normal sitting behaviour or another control intervention.

Types of outcome measures

Primary outcomes

We list primary and secondary outcomes below. If a study was otherwise eligible (i.e. correct study design, population and intervention/comparator) but did not report a listed outcome then we planned to contact the study authors, where possible, to establish whether an outcome of interest to the review was measured but not reported.

We planned to report outcome measures at the latest time point available for a study (assumed to be length of follow‐up, if not specified) and the time point specified in the methods as being of primary interest (if this was different from latest time point available). For all outcomes we planned to categorise outcomes as follows:

SHORT TERM: those occurring before eight weeks;
MEDIUM TERM; those occurring between eight and 26 weeks; and
LONG TERM: those occurring after 26 weeks.

The primary outcomes for this review were complete wound healing and adverse events.

Complete wound healing

For this review we regarded the following as providing the most relevant and rigorous measures of outcome:

time to complete wound healing: we planned to record whether this has been correctly analysed using censored data and with adjustment for prognostic covariates such as baseline size;
the proportion of ulcers healed (frequency of complete healing).

Where both the outcomes above were reported we planned to present all data in a summary outcome table for reference. Where equal amounts of information were available we anticipated focusing on time to healing as the key outcome measure. We planned to accept authors’ definitions of what constituted a healed wound.

Adverse events (specified as important by our consumer advisors)

Incidence of a new pressure ulcer;
Incidence of chest infection;
Reports of muscle deterioration;
Time to recovery following period of bed rest.

Secondary outcomes

Mean pain scores (measured at any time with any validated instrument e.g. Visual Analogue Scale).
Mean health‐related quality of life (using any validated measure such WHOQOL‐BREF, SF‐36, SF‐12).
Cost (including resources associated with the team and those associated with dressings and other additional interventions, where reported).
Adverse events (generic). Reported data were to be extracted on adverse events classed as 'serious adverse events' and 'non‐serious adverse events' where a clear methodology for the collection of adverse event data was provided. This methodology would have been needed to make it clear whether events were reported at the participant level or, where multiple events/person were reported, that an appropriate adjustment had been made for data clustering. Individual types of adverse events such as pain or infection that required specific assessment were not planned to be extracted under this outcome ‐ rather this was to be the assessment of any event classed as adverse by the patient and or health professional during the trial.

Search methods for identification of studies

Electronic searches

We searched the following electronic databases to identify reports of relevant randomised clinical trials:

The Cochrane Wounds Specialised Register (searched 10 October 2016);
The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library) (2016, Issue 9);
Ovid MEDLINE (including In‐Process & Other Non‐Indexed Citations, MEDLINE Daily and Epub Ahead of Print) (1946 to 10 October 2016);
Ovid EMBASE (1974 to 10 October 2016);
EBSCO CINAHL Plus (1937 to 10 October 2016).

The search strategies for CENTRAL, Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL Plus can be found in Appendix 1. We combined the Ovid MEDLINE search 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). We did not restrict studies with respect to language, date of publication or study setting.

We also searched the following clinical trials registries for ongoing and unpublished studies:

Clinical Trials.gov (www.clinicaltrials.gov) (searched 11th October 2016);
WHO International Clinical Trials Registry Platform (ICTRP) apps.who.int/trialsearch/Default.aspx) (searched 11th October 2016);
The EU Clinical Trials Register (www.clinicaltrialsregister.eu) (searched 11th October 2016).

Searching other resources

We planned to search reference lists of all included studies. We searched other relevant publications, such as systematic reviews and guidelines. We contacted experts in the field and planned to contact the authors of relevant publications to identify any completed or ongoing trials. We also performed manual searches of conference proceedings, namely the National Pressure Ulcer Advisory Panel Conference, USA; the European Pressure Ulcer Advisory Panel meeting; the Pan Pacific Pressure Injury Alliance meeting; and the World Union of Wound Healing Societies meeting, to identify authors and papers related primarily to bed rest for the treatment of pressure ulcers.

Data collection and analysis

We performed this systematic review according to instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Green 2011).

Selection of studies

Two review authors (ZM and MvE) independently assessed the titles and abstracts of the citations retrieved by the searches for relevance. After this initial assessment, we planned to obtain full text copies of all studies felt to be potentially relevant. Independently, two review authors planned to check the full papers for eligibility; disagreements were to be resolved by discussion and, where required, the input of a third review author. We planned to record all reasons for the exclusion of studies for which we had obtained full copies. We completed a PRISMA flowchart to summarize this process (Liberati 2009).

Where studies were reported multiple times we planned to obtain all publications. Whilst the study would have been included only once in the review, we planned to extract data from all reports to ensure we obtained the maximal amount of relevant data.

Data extraction and management

We planned to extract and summarize details of the eligible studies. Two review authors were to extract data independently and resolve disagreements by discussion, drawing on a third review author where required. Where data were missing from reports, we planned to attempt to contact the study authors to obtain this information. Where a study with more than two intervention arms would have been included, only data from intervention and control groups that meet the eligibility criteria were to be extracted.

We planned to extract the following data, where possible by treatment group, for the prespecified interventions and outcomes in this review using a data extraction sheet developed for this purpose:

author, title, source;
date of study, country of origin;
care setting;
inclusion and exclusion criteria;
baseline participant characteristics (ulcer grade and size);
number of participants randomised to each arm;
study design details;
risk of bias;
intervention details (specifically team composition and focus of the intervention), concurrent intervention(s);
type of surface the person was lying on;
primary and secondary outcomes (with definitions);
length of follow‐up;
loss to follow‐up;
outcomes data for primary and secondary outcomes (by group);
funding source.

One review author (ZM) was to enter data into Review Manager 5 (RevMan 5) 5.3 software (RevMan 2014), with a second author (MvE) verifying accuracy.

Assessment of risk of bias in included studies

Two review authors (ZM and MvE) planned to use the Cochrane 'Risk of bias' tool to independently assess the risk of bias of the included studies (Higgins 2011a). This tool addresses six specific domains, namely: sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other issues (e.g. extreme baseline imbalance, which might inform decisions about selection bias). Appendix 2 contains details of the criteria on which this assessment was to be based. We were to assess blinding and completeness of outcome data for each outcome separately (for example, blinding is important for subjective outcomes such as pressure ulcer healing and pain). We planned to present our assessment of risk of bias using a 'Risk of bias' summary figure that shows a summary of all of the 'Risk of bias' items. For studies using cluster randomisation, we were also to assess the following domains for risk of bias: recruitment bias, baseline imbalance, loss of clusters, incorrect analysis and comparability with individually randomised trials (Higgins 2011b).

Measures of treatment effect

For dichotomous outcomes (e.g. proportion of participants with a pressure ulcer healed) we planned to calculate the risk ratio (RR) with 95% confidence intervals (CI). For continuously distributed outcome data (e.g. pain), when all trials used the same assessment scale we planned to use the mean difference (MD) with 95% CIs. If trials used different assessment scales, we planned to use the standardised mean difference (SMD) with 95% CIs. We planned to report time‐to‐event data (e.g. time to complete wound healing) as hazard ratios (HR) where possible, in accordance with the methods described in the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). For statistically significant effects in binary outcomes we planned to calculate number needed to treat for an additional beneficial outcome (NNTB), or number needed to treat for an additional harmful outcome (NNTH). Where skewness was suspected, and if scale data had finite upper and lower limits, we planned to use the easy 'rule of thumb' calculation to test for skewness. That is, if the standard deviation (SD), when doubled, was greater than the mean, it would be unlikely that the mean was the centre of the distribution (Altman 1996), and we planned not to enter the data into any meta‐analysis. If we found relevant data that were skewed, we planned to present the data in 'Other data' tables.

Unit of analysis issues

Where studies were randomised at the participant level and measured outcomes at the wound level, for example for wound healing, and the number of wounds appeared to be equal to the number of participants, we planned to treat the participant as the unit of analysis. We anticipated a possible unit of analysis issue if individual participants with multiple wounds were randomised, the allocated treatment implemented and then data presented and analysed by wound not person. This is a type of clustered data and presents a unit of analysis error that inflates precision. In cases where included studies contained some or all clustered data we planned to report this alongside whether data had been (incorrectly) treated as being independent. We planned to record this as part of the 'Risk of bias' assessment. We did not plan to undertake further calculation to adjust for clustering in these cases.

Dealing with missing data

Where possible, we planned to perform all analyses using the intention‐to‐treat (ITT) principle, that is, all randomised participants should have been analysed according to their allocated treatment group. Where it appeared that data were excluded from the analyses, we planned to contact authors for these missing data. If data remained missing, despite our best efforts to obtain them, we planned to assume that those missing from the analysis of dichotomous data had a negative outcome (e.g. did not heal completely). For continuous data, if standard deviations were missing, where possible, we planned to compute them from standard errors (SE) using the formula SD = SE x √N (Higgins 2011c). If this were not possible, and trial authors were not able to provide data, we would have been unable to present these data. Where results were reported for all participants, but it was unclear how many people were originally randomised, we planned to use an available‐case analysis.

Assessment of heterogeneity

Assessment of heterogeneity can be a complex, multi‐faceted process. Firstly, we planned to consider clinical and methodological heterogeneity: that is the degree to which the included studies varied in terms of participant, intervention, outcome and characteristics such as length of follow‐up. This assessment of clinical and methodological heterogeneity was to be supplemented by information regarding statistical heterogeneity ‐ assessed using the Chi² test (a significance level of P < 0.10 was to be considered to indicate statistically significant heterogeneity) in conjunction with the I² statistic (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). Where there was evidence of high heterogeneity we planned to attempt to explore this further: see Data synthesis.

Assessment of reporting biases

Reporting bias was to be assessed using guidelines in the Cochrane Handbook for Systematic Reveiws of Interventions (Stern 2011). If enough studies were available for a meaningful assessment of publication bias, we planned to construct a funnel plot of primary outcomes to test for asymmetry. We also planned to consider selective reporting (i.e. reporting some outcomes and not others) in our assessment of reporting bias.

Data synthesis

We planned to combine details of included studies in a narrative review according to type of comparator, possibly by location/type of wound and then by outcomes and time period. We planned to consider clinical and methodological heterogeneity and undertake pooling when studies appeared to be appropriately similar in terms of wound type, intervention type, duration of follow‐up and outcome type, that is, when synthesis was considered viable. Our standard approach for meta‐analytical analyses was to employ a random‐effects model. The basis for our preference for the more conservative random‐effects model was that statistical assessments can miss potentially important between‐study heterogeneity in small samples (Kontopantelis 2012). We planned to only use a fixed‐effect analysis when, in our judgement, there was minimal clinical heterogeneity and this was also supported by an Chi² value that was estimated to be statistically non‐significant and an I² of 0% (Kontopantelis 2013). In all other circumstances a random‐effects model was to be adopted. Where clinical heterogeneity was thought to be acceptable, or of interest, we planned to meta‐analyse even when statistical heterogeneity was high, but would have attempted to interpret the causes behind this heterogeneity and would have considered using meta‐regression for that purpose, if possible (Thompson 1999; Thompson 2002).

Data were to be presented using forest plots where possible. For dichotomous outcomes we planned to present the summary estimate as a RR with 95% CIs. Where continuous outcomes were measured in the same way across studies, we planned to present a pooled MD with 95% CIs; we planned to pool SMD estimates where studies measured the same outcome using different methods. For time‐to‐event data, we planned to plot and, if appropriate, pool estimates of hazard ratios and 95% CIs as presented in the study reports using the generic inverse variance method in RevMan 5.3 (RevMan 2014). Where time to healing was analysed as a continuous measure, but it was not clear if all wounds healed, use of the outcome in the study would have been documented, but we would not have summarised or used data in any meta‐analysis. We planned to obtain pooled estimates of treatment effect by using the Cochrane RevMan 5.3 software (RevMan 2014).

Subgroup analysis and investigation of heterogeneity

If substantial heterogeneity existed between studies for the primary outcomes (that is, when the I² statistic exceeded 50%), we planned to explore reasons for heterogeneity. We envisaged that the number of studies meeting our inclusion criteria would have been low. Consequently, to avoid type I errors we planned to conduct a minimal number of sub analyses that were to include the following, if possible:

type of intervention (complete bed rest versus periodic bed rest).

Sensitivity analysis

If feasible we planned to perform a sensitivity analysis by excluding those studies assessed as having a high risk of bias in the key domains of selection bias and detection bias. Again, if feasible we planned to explore the effect of excluding cluster trials, where the analysis was not at the same level as the allocation (i.e. allocation by cluster and analysis by individual).

'Summary of findings' tables

We planned to present the main results of the review in 'Summary of findings’ tables. These tables present key information concerning the quality 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 (Grades of Recommendation, Assessment, Development and Evaluation) approach. The GRADE approach defines the quality 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 quality 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 planned to present the following outcomes in the 'Summary of findings’ tables:

ulcer healing;
incidence of new pressure ulcer;
incidence of chest infection.

Where data were not pooled we planned to conduct the GRADE assessment for each comparison and present this narratively within the results section, without the presentation of separate 'Summary of findings' tables.

Results

Description of studies

Results of the search

The search yielded 73 citations (see Figure 1). ZM and MvE examined the abstracts of all papers, independently, to assess for potential relevance. Following this assessment, no papers met the inclusion criteria. ZM contacted 19 experts in the field enquiring about further potential papers, and no further papers were identified.

Figure 1