Treatment effect sizes vary in randomized trials depending on the type of outcome measure

Research output: Contribution to journalComment/debateResearch

  • Dorthe B. Berthelsen
  • Elisabeth Ginnerup-Nielsen
  • Carsten Juhl
  • Hans Lund
  • Henriksen, Marius
  • Asbjørn Hróbjartsson
  • Sabrina M. Nielsen
  • Marieke Voshaar
  • Robin Christensen

Objective: To compare estimated treatment effects of physical therapy (PT) between patient-reported outcome measures (PROMs) and outcomes measured in other ways. Study Design and Setting: We selected randomized trials of PT with both a PROM and a non-PROM included in Cochrane systematic reviews (CSRs). Two reviewers independently extracted data and risk-of-bias assessments. Our primary outcome was the ratio of odds ratios (RORs), used to quantify how effect varies between PROMs and non-PROMs; an ROR > 1 indicates larger effect when assessed by using PROMs. We used REML-methods to estimate associations of trial characteristics with effects and between-trial heterogeneity. Results: From 90 relevant CSRs, 205 PT trials were included. The summary ROR across all the comparisons was not statistically significant (ROR, 0.88 [95% CI: 0.70–1.12]; P = 0.30); however, the heterogeneity was substantial (I2 = 88.1%). When stratifying non-PROMs further into clearly objective non-PROMs (e.g., biomarkers) and other non-PROMs (e.g., aerobic capacity), the PROMs appeared more favorable than did clearly objective non-PROMs (ROR, 1.92 [95% CI: 0.99–3.72]; P = 0.05). Conclusion: Estimated treatment effects based on PROMs are generally comparable with treatment effects measured in other ways. However, in our study, PROMs indicate a more favorable treatment effect compared with treatment effects based on clearly objective outcomes.

Original languageEnglish
JournalJournal of Clinical Epidemiology
Volume123
Pages (from-to)27-38
ISSN0895-4356
DOIs
Publication statusPublished - 2020

    Research areas

  • Effect size, Meta-epidemiology, Meta-Research, Patient-involvement, Patient-reported outcome measures, Physical therapy

ID: 249815073