Abstract
ObjectiveThere is debate on how the methodological quality of clinical trials should be assessed. We compared trials of physical therapy (PT) judged to be of adequate quality based on summary scores from the Physiotherapy Evidence Database (PEDro) scale with trials judged to be of adequate quality by Cochrane Risk of Bias criteria.DesignMeta-epidemiological study within Cochrane Database of Systematic Reviews.MethodsMeta-analyses of PT trials were identified in the Cochrane Database of Systematic Reviews. For each trial PeDro and Cochrane assessments were extracted from the PeDro and Cochrane databases. Adequate quality was defined as adequate generation of random sequence, concealment of allocation, and blinding of outcome assessors (Cochrane criteria) or as trials with a PEDro summary score ≥5 or ≥6 points. We combined trials of adequate quality using random-effects meta-analysis.ResultsForty-one Cochrane reviews and 353 PT trials were included. All meta-analyses included trials with PEDro scores ≥5, 37 (90.2%) included trials with PEDro scores ≥6 and only 22 (53.7%) meta-analyses included trials of adequate quality according to the Cochrane criteria. Agreement between PeDro and Cochrane was poor for PeDro scores of ≥5 points (kappa = 0.12; 95% CI 0.07 to 0.16) and slight for ≥6 points (kappa 0.24; 95% CI 0.16-0.32). When combining effect sizes of trials deemed to be of adequate quality according to PEDro or Cochrane criteria, we found that a substantial difference in the combined effect size (≥0.15) was evident in 9 (22%) out of the 41 meta-analyses for PEDro cutoff ≥5 and 10 (24%) for cutoff ≥6.ConclusionsThe PeDro and Cochrane approaches lead to different sets of trials of adequate quality, and different combined treatment estimates from meta-analyses of these trials. A consistent approach to assessing RoB in trials of physical therapy should be adopted.
Highlights
Randomized controlled trials (RCTs) are the design of choice when comparing two or more healthcare interventions
Agreement between PeDro and Cochrane was poor for PeDro scores of 5 points and slight for 6 points
When combining effect sizes of trials deemed to be of adequate quality according to PEDro or Cochrane criteria, we found that a substantial difference in the combined effect
Summary
Randomized controlled trials (RCTs) are the design of choice when comparing two or more healthcare interventions. Conducted RCTs minimize confounding and bias and allow causal inferences regarding the effects of interventions. When not appropriately done, RCTs may yield biased estimates [1,2,3,4,5,6]. It is imperative to consider the risk of bias (RoB) in RCTs when reviewing evidence for clinical decision making. The importance of incorporating RoB assessments in evidence synthesis is widely recognized. The approaches to perform such assessments have been inconsistent: a wide variety of checklists and scales have been developed to evaluate RoB in RCTs [7,8,9]. The use of different items varies between tools, some items are used without empirical evidence or theoretical rationale, and different checklists and scales are used in different research areas, suggesting lack of agreement regarding their relevance [7]
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