The Unknown Prevalence of Postrandomization Bias in 15 Physical Therapy Journals: A Methods Review

Abstract

Objectives To determine the prevalence of prospective clinical trial registration and postrandomization bias in published musculoskeletal physical therapy randomized clinical trials (RCTs). Design A methods review. Literature Search Articles indexed in MEDLINE and published between January 2016 and July 2020 were included. Study Selection Criteria Two independent blinded reviewers identified the RCTs using Covidence. We included RCTs related to musculoskeletal interventions that were published in International Society of Physiotherapy Journal Editors member journals. Data Synthesis Data were extracted independently for the variables of interest from the identified RCTs by 2 blinded reviewers. The data were presented descriptively or in frequency tables. Results One hundred thirty-eight RCTs were identified. One third of RCTs were consistent with their prospectively registered intent (49/138); consistency with prospectively registered intent could not be determined for two thirds (89/138) of the RCTs. Four RCTs (8%)reported inconsistent results with the primary aims and 7 (14%) with the outcomes from the prospective clinical trial registry, despite high methodological quality (Physiotherapy Evidence Database [PEDro] scale score). Differences between prospectively registered and non-prospectively registered RCTs for PEDro scale scores had a medium effect size (r = 0.30). Two of 15 journals followed their clinical trial registration policy 100% of the time; in 1 journal, the published RCTs were consistent with the clinical trial registration. Conclusion Postrandomization bias in musculoskeletal physical therapy RCTs could not be ruled out, due to the lack of prospective clinical trial registration and detailed data analysis plans. J Orthop Sports Phys Ther 2021;51(11):542–550. Epub 21 Sep 2021. doi:10.2519/jospt.2021.10491

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