Many tools and individual items have been suggested to assess methodological quality of randomized controlled trials (RCTs). The frequency of use of these items varies according to health area, which indicate a lack of agreement regarding their relevance to trial quality or risk of bias (RoB). The aim of this study was to identify the underlying component structure of items and determine relevant items to evaluate quality/RoB of trials in physical therapy (PT) by using an exploratory factor analysis (EFA). Methodological research, EFAMethodsRCTs used for this study were randomly selected from searches of the Cochrane Database of Systematic Reviews. Two reviewers used 45 items gathered from seven different quality tools to assess RCTs methodological quality. An exploratory factor analysis using Principal Axis Factoring (PAF) method followed by Varimax rotation was conducted.ResultsPAF identified 34 items loaded on 9 common factors: 1) selection bias; 2) performance and detection bias; 3) eligibility, interventions details, and description of outcomes measures; 4) psychometric properties of main outcome; 5) contamination and compliance; 6) attrition bias; 7) data analysis; 8) sample size; 9) control and placebo adequacy. Due to the exploratory nature of the results, a confirmatory factor analysis is necessary to validate this model.
To the authors knowledge, this was the first factor analysis to explore the underlying component items used to evaluate methodological quality/risk of bias of RCTs in PT. The items and/or factors represent a starting point for evaluating the methodological quality/RoB in PT trials. Empirical evidence of the association between these items with treatment effects and also a confirmatory factor analysis of these results is needed to validate these items.