Bed rest for pressure ulcer healing in wheelchair users
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the impact of bed rest on healing pressure ulcers in wheelchair users, of any age, who are living or being cared for in any setting.
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 activity or mobility problems and so are exposed to prolonged periods of exposure to sustained pressure/shear forces (Gefen 2008). The elderly, those with spinal cord injury and those who are sedated following trauma or surgery are at 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 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 suggest 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) and buttocks, the coccyx and upper thighs (Stockton 2002). When sitting the weight of the individual is forced against the supporting seat surface, compressing the soft tissues and increasing risk of pressure ulceration, therefore, regular repositioning ‐ as often as every 15 to 30 minutes ‐ is recommended for those 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 1 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 1 and above; Sheerin 2011). In another study undertaken between 1986 and 2002 of 3361 people with spinal cord injury, 27% 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 1 or greater). 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 those with spinal cord injury and pressure ulcers are compared with controls (spinal cord injured wheelchair users without pressure ulcers), they reported significantly lower scores (worse health status) on all SF‐36 subscales (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 cells, so the metabolic need of the wounded area is great (Krishnamoothy 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 weight bear 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 increasing the 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 (Gunnar 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 remain an important issue for those confined to a wheelchair, therefore adopting strategies aimed at reducing their healing time makes both human and economic sense (Moore 2014), however, the possible risks associated with bed rest as a treatment also need to be assessed systematically. Although there have been many reports about the use 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 is 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 healing pressure ulcers 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 will be eligible for inclusion, irrespective of language of report. Cross‐over trials will be eligible if outcome data are available from the end of the first treatment period prior to cross‐over. Studies using quasi‐randomisation will 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), will be eligible for inclusion.
Types of interventions
The intervention of interest is bed rest (as defined by study authors, but must involve a period of non‐seated time, so may include complete bed rest or periodic bed rest, or both) used for the treatment of pressure ulcers in wheelchair users. The comparison will be normal sitting behaviour or another control intervention.
Types of outcome measures
Primary outcomes
We list primary and secondary outcomes below. If a study is otherwise eligible (i.e. correct study design, population and intervention/comparator) but does not report a listed outcome then we will contact the study authors, where possible, to establish whether an outcome of interest to the review was measured but not reported.
We will 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 will categorise outcomes from:
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less than a week to eight weeks as short term;
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eight weeks to 26 weeks as medium term; and
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over 26 weeks as long term.
Primary outcomes
The primary outcomes for this review are 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:
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time to complete wound healing: we will record whether this has been correctly analysed using censored data and with adjustment for prognostic covariates such as baseline size;
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the proportion of ulcers healed (frequency of complete healing).
Where both the outcomes above are reported we will present all data in a summary outcome table for reference. Where equal amounts of information are available we anticipate focusing on time to healing as the key outcome measure. We will accept authors’ definitions of what constituted a healed wound.
Adverse events (specified as important by our consumer advisors)
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Incidence of a new pressure ulcer.
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Incidence of chest infection.
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Reports of muscle deterioration.
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Time to recovery following period of bed rest.
Secondary outcomes
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Mean pain scores (measured at any time with any validated instrument e.g. Visual Analogue Scale).
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Mean health‐related quality of life (using any validated measure such WHOQOL‐BREF, SF‐36, SF‐12).
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Cost (including resources associated with the team and those associated with dressings and other additional interventions, where reported).
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Adverse events (generic). Reported data will 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 is provided. This methodology is needed to make it clear whether events are reported at the participant level or, where multiple events/person are reported, that an appropriate adjustment has been made for data clustering. Individual types of adverse events such as pain or infection that require specific assessment will not be extracted under this outcome ‐ rather this is 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 will search the following electronic databases to identify reports of relevant randomised clinical trials:
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The Cochrane Wounds Group Specialised Register;
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The Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library; latest issue);
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Ovid MEDLINE (1946 to present);
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Ovid EMBASE (1974 to present);
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EBSCO CINAHL (1982 to present).
We will use the following strategy for CENTRAL (other strategies are presented in Appendix 1):
ID Search
#1 MeSH descriptor: [Pressure Ulcer] explode all trees
#2 (pressure next (ulcer* or sore* or injur*)):ti,ab,kw (Word variations have been searched)
#3 (decubitus next (ulcer* or sore*)):ti,ab,kw (Word variations have been searched)
#4 ((bed next sore*) or bedsore*):ti,ab,kw (Word variations have been searched)
#5 {or #1‐#4}
#6 MeSH descriptor: [Wheelchairs] explode all trees
#7 (wheelchair* or (wheel* N/3 (chair* or mobil*))):ti,ab,kw (Word variations have been searched)
#8 (mobile N/4 (seat* or chair*)):ti,ab,kw (Word variations have been searched)
#9 {or #6‐#8}
#10 MeSH descriptor: [Bed Rest] explode all trees
#11 (bedrest* or "bed rest" or (bed* adj3 rest*)):ti,ab,kw (Word variations have been searched)
#12 {or #10‐#11}
#13 {and #5, #9, #12}
We will adapt this strategy to search Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL. We will combine 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 will combine the EMBASE search with the Ovid EMBASE filter developed by the UK Cochrane Centre (Lefebvre 2011). We will combine the CINAHL searches with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN 2010). We will not restrict studies with respect to language, date of publication or study setting.
We will also search the following clinical trials registries:
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Clinical Trials.gov (http://www.clinicaltrials.gov/);
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WHO International Clinical Trials Registry Platform (ICTR; http://apps.who.int/trialsearch/Default.aspx);
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The EU Clinical Trials Register (https://www.clinicaltrialsregister.eu/).
Searching other resources
We will search reference lists of all included studies and other relevant publications, such as systematic reviews and guidelines. We will contact experts in the field and the authors of relevant publications to identify any completed or ongoing trials. We will also perform manual searches of conference proceedings, such as 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 will perform this systematic review according to instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Green 2011).
Selection of studies
Two review authors will independently assess the titles and abstracts of the citations retrieved by the searches for relevance. After this initial assessment, we will obtain full text copies of all studies felt to be potentially relevant. Independently, two review authors will check the full papers for eligibility; disagreements will be resolved by discussion and, where required, the input of a third review author. We will record all reasons for the exclusion of studies for which we have obtained full copies. We will completed a PRISMA flowchart to summarise this process (Moher 2009).
Where studies are reported multiple times we will obtain all publications. Whilst the study will be included only once in the review, we will extract data from all reports to ensure we obtain the maximal amount of relevant data.
Data extraction and management
We will extract and summarise details of the eligible studies. Two review authors will extract data independently and resolve disagreements by discussion, drawing on a third review author where required. Where data are missing from reports, we will attempt to contact the study authors to obtain this information. Where a study with more than two intervention arms is included, only data from intervention and control groups that meet the eligibility criteria will be extracted.
We will extract the following data, where possible by treatment group, for the pre‐specified interventions and outcomes in this review using a data extraction sheet developed for this purpose:
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author, title, source;
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date of study, country of origin;
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care setting;
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inclusion and exclusion criteria;
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baseline participant characteristics (ulcer grade and size);
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number of participants randomised to each arm;
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study design details;
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risk of bias;
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intervention details (specifically team composition and focus of the intervention), concurrent intervention(s);
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type of surface the person is lying on;
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primary and secondary outcomes (with definitions);
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length of follow‐up;
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loss to follow‐up;
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outcomes data for primary and secondary outcomes (by group);
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funding source.
One review author (ZM) will enter data into Review Manager (RevMan) 5.3 software (RevMan 2014), with a second author (MvE) verifying accuracy.
Assessment of risk of bias in included studies
Independently, two review authors (ZM and MvE) will use the Cochrane 'Risk of bias' tool to 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 will be based. We will 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 will 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 will also 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 plan to calculate the risk ratio (RR) with 95% confidence intervals (CI). For continuously distributed outcome data (e.g. pain), when all trials use the same assessment scale we plan to use the mean difference (MD) with 95% CIs. If trials use different assessment scales, we plan to use the standardised mean difference (SMD) with 95% CIs. We plan 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 plan to calculate number needed to treat to benefit (NNTB), or number needed to treat to harm (NNTH). Where skewness is suspected, and if scale data have finite upper and lower limits, we plan to use the easy 'rule of thumb' calculation to test for skewness. That is, if the standard deviation (SD), when doubled, is greater than the mean, it is unlikely that the mean is the centre of the distribution (Altman 1996), and we plan not to enter the data into any meta‐analysis. If we find relevant data that are skewed, we plan to present the data in 'Other data' tables.
Unit of analysis issues
Where studies randomise at the participant level and measure outcomes at the wound level, for example for wound healing, and the number of wounds appears to be equal to the number of participants, we will treat the participant as the unit of analysis. We anticipate a possible unit of analysis issue if individual participants with multiple wounds are 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 contain some or all clustered data we plan to report this alongside whether data have been (incorrectly) treated as being independent. We will record this as part of the risk of bias assessment. We do not plan to undertake further calculation to adjust for clustering in these cases.
Dealing with missing data
Where possible, we plan to perform all analyses using the intention‐to‐treat (ITT) principle, that is, participants should be analysed according to their allocated treatment group. Where it appears that data were excluded from the analyses, we plan to contact authors for these missing data. If data remain missing, despite our best efforts to obtain them, we will 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 are missing, where possible, we plan to compute them from standard errors (SE) using the formula SD = SE x √N (Higgins 2011c). If this is not possible, and trial authors are not able to provide data, we will be unable to present these data. Where results are reported for all participants, but it is unclear how many people were originally randomised, we plan to use an available‐case analysis.
Assessment of heterogeneity
Assessment of heterogeneity can be a complex, multi‐faceted process. Firstly, we will consider clinical and methodological heterogeneity: that is the degree to which the included studies vary in terms of participant, intervention, outcome and characteristics such as length of follow‐up. This assessment of clinical and methodological heterogeneity will be supplemented by information regarding statistical heterogeneity ‐ assessed using the Chi² test (a significance level of P < 0.10 will 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 is evidence of high heterogeneity we will attempt to explore this further: see Data synthesis.
Assessment of reporting biases
Reporting bias will be assessed using guidelines in the Cochrane Handbook for Systematic Reveiws of Interventions (Stern 2011). If enough studies are available for a meaningful assessment of publication bias, we plan to construct a funnel plot of primary outcomes to test for asymmetry. We will also consider selective reporting (i.e. reporting some outcomes and not others) in our assessment of reporting bias.
Data synthesis
We will 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 will consider clinical and methodological heterogeneity and undertake pooling when studies appear to be appropriately similar in terms of wound type, intervention type, duration of follow‐up and outcome type, that is, when synthesis is considered viable. Our standard approach for meta‐analytical analyses will be to employ a random‐effects model. The basis for our preference for the more conservative random‐effects model is that statistical assessments can miss potentially important between‐study heterogeneity in small samples (Kontopantelis 2012). We will only use a fixed‐effect analysis when, in our judgement, there is minimal clinical heterogeneity and this is also supported by an Chi² value that is estimated to be statistically non‐significant and an I² of 0% (Kontopantelis 2013). In all other circumstances a random‐effects model will be adopted. Where clinical heterogeneity is thought to be acceptable, or of interest, we may meta‐analyse even when statistical heterogeneity is high, but we will attempt to interpret the causes behind this heterogeneity and will consider using meta‐regression for that purpose, if possible (Thompson 1999; Thompson 2002)
Data will be presented using forest plots where possible. For dichotomous outcomes we will present the summary estimate as a RR with 95% CIs. Where continuous outcomes are measured in the same way across studies, we plan to present a pooled MD with 95% CIs; we plan to pool SMD estimates where studies measure the same outcome using different methods. For time‐to‐event data, we plan 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 is analysed as a continuous measure, but it is not clear if all wounds healed, use of the outcome in the study will be documented but we will not summarise or use data in any meta‐analysis. We will 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 exists between studies for the primary outcomes (that is, when the I² statistic exceeds 50%), we plan to explore reasons for heterogeneity. We envisage that the number of studies meeting our inclusion criteria may be low. Consequently, to avoid type 1 errors we plan to conduct a minimal number of sub‐analyses that will include the following, if possible:
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type of intervention (complete bed rest versus periodic bed rest).
Sensitivity analysis
If feasible we plan 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 will also explore the effect of excluding cluster trials, where the analysis is not at the same level as the allocation (i.e. allocation by cluster and analysis by individual).
'Summary of findings' tables
We will 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 plan to present the following outcomes in the 'Summary of findings’ tables:
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ulcer healing;
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incidence of new pressure ulcer;
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incidence of chest infection.
Where data are not pooled we will conduct the GRADE assessment for each comparison and present this narratively within the results section, without the presentation of separate 'Summary of findings' tables.
