Identifying Items to Assess Methodological Quality in Physical Therapy Trials: A Factor Analysis

Background. Numerous tools and individual items have been proposed to assess the methodological quality of randomized controlled trials (RCTs). The frequency of use of these items varies according to health area, which suggests a lack of agreement regarding their relevance to trial quality or risk of bias. Objective. The objectives of this study were: (1) to identify the underlying component structure of items and (2) to determine relevant items to evaluate the quality and risk of bias of trials in physical therapy by using an exploratory factor analysis (EFA). Design. A methodological research design was used, and an EFA was performed. Methods. Randomized controlled trials used for this study were randomly selected from searches of the Cochrane Database of Systematic Reviews. Two review-ers used 45 items gathered from 7 different quality tools to assess the methodological quality of the RCTs. An exploratory factor analysis was conducted using the principal axis factoring (PAF) method followed by varimax rotation. Results. Principal axis factoring identified 34 items loaded on 9 common factors