Interpreting Patient-Reported Outcome Measures in Orthopaedic Surgery: A Systematic Review

Background: The Consolidated Standards of Reporting Trials (CONSORT) Statement recommends that studies report results beyond p values and include treatment effect(s) and measures of precision (e.g., confidence intervals [CIs]) to facilitate the interpretation of results. The objective of this systematic review was to assess the reporting and interpretation of patient-reported outcome measure (PROM) results in clinical studies from high-impact orthopaedic journals, to determine the proportion of studies that (1) only reported a p value; (2) reported a treatment effect, CI, or minimal clinically important difference (MCID); and (3) offered an interpretation of the results beyond interpreting a p value.

Methods: We included studies from 5 high-impact-factor orthopaedic journals published in 2017 and 2019 that compared at least 2 intervention groups using PROMs.

Results: A total of 228 studies were analyzed, including 126 randomized controlled trials, 35 prospective cohort studies, 61 retrospective cohort studies, 1 mixed cohort study, and 5 case-control studies. Seventy-six percent of studies (174) reported p values exclusively to express and interpret between-group differences, and only 22.4% (51) reported a treatment effect (mean difference, mean change, or odds ratio) with 95% CI. Of the 54 studies reporting a treatment effect, 31 interpreted the results using an important threshold (MCID, margin, or Cohen d), but only 3 interpreted the CIs. We found an absolute improvement of 35.5% (95% CI, 20.8% to 48.4%) in the reporting of the MCID between 2017 and 2019.

Conclusions: The majority of interventional studies reporting PROMs do not report CIs around between-group differences in outcome and do not define a clinically meaningful difference. A p value cannot effectively communicate the readiness for implementation in a clinical setting and may be misleading. Thus, reporting requirements should be expanded to require authors to define and provide a rationale for between-group clinically important difference thresholds, and study findings should be communicated by comparing CIs with these thresholds.