Patient-important outcomes account for fewer than half of reported outcomes and are synthesized differently from surrogate outcomes in rehabilitation systematic reviews

BACKGROUND AND OBJECTIVES: Systematic reviews (SRs) support patient-centered decision-making and should therefore synthesize evidence about outcomes that are most important to patients. Rehabilitation is a core component of health systems worldwide, yet little is known about whether SRs in this field adequately address patient-important outcomes (PIOs). To support the patient-centeredness of evidence used to inform rehabilitation decisions, this study aimed to (1) determine the frequency of patient-important outcomes (PIOs) and how they are reported and (2) compare outcome reporting and synthesis methods between patient-important and surrogate outcomes in SRs of rehabilitation interventions. METHODS: We conducted a methodological study of SRs evaluating rehabilitation interventions. We searched MEDLINE, Embase, PsycINFO, and the Cochrane Library up to October 31, 2024. We included SRs published within the previous 5 years to assess current reporting and synthesis practices. We included SRs of randomized controlled trials evaluating rehabilitation interventions. SRs explicitly focused on rehabilitation interventions or targeted impairments in body functions. We distinguished outcome constructs from outcome measures and characterized outcomes across methodological and functional dimensions. Using outcome measures as the unit of analysis, reviewers classified each as PIO or surrogate and extracted outcome-level reporting and synthesis characteristics. We estimated the prevalence of PIOs at the outcome and SR levels and compared reporting and synthesis characteristics using descriptive statistics, clustered logistic regression, and nonparametric tests. RESULTS: We included 98 SRs that reported 432 outcome constructs and 580 outcome measures. At the outcome level, PIOs accounted for 41.7% of outcome measures and 49.2% of outcome constructs. At the SR level, 74.5% of SRs reported at least 1 PIO measure. In 16% of SRs, at least 1 outcome construct identified as patient-important was summarized using a surrogate measure. Compared with surrogate outcomes, PIOs were less likely to be synthesized using meta-analysis (59.1% vs 70.7%), less often analyzed as continuous variables (69.4% vs 93.8%), and more often measured using patient-reported measures (55.4% vs 2.2%). CONCLUSION: PIOs are underrepresented in rehabilitation SRs and are synthesized differently from surrogate outcomes. This limits the extent to which evidence syntheses can support patient-centered decision-making and highlights the need to improve outcome selection in research.