Enhancing reporting and interpretation of surrogate endpoints in rehabilitation randomized controlled trials: a scoping review

Purpose: This study aimed to identify and audit rehabilitation randomized controlled trials (RCTs) that used surrogate endpoints, evaluating the completeness and transparency of reporting based on the recently developed SPIRIT- (Standard Protocol Items: Recommendations for Interventional Trials) and CONSORT- (Consolidated Standards of Reporting Trials) surrogate extension checklists. Methods: A scoping review was performed, analyzing RCTs from the MEDLINE, PEDro, CINAHL, EMBASE, and SCOPUS databases up to April 29th, 2025. Included studies involved live human participants and investigated non-pharmacological interventions affecting health outcomes, with surrogate endpoints linked to target outcomes. Both qualitative and quantitative analyses were conducted using the SPIRIT and CONSORT-surrogate checklists for reporting compliance. Results: Out of 3,316 records, 20 RCTs were included. Most studies were published between 2004 and 2024, primarily post-2011 and from high-income countries. All three protocol registries found scored zero on the SPIRIT-surrogate checklist. Multiple surrogate endpoints were identified, chiefly as biomarkers. Only 30% (n = 6 RCTs) met at least 50% of the CONSORT-surrogate checklist items in their final reports. Conclusions: Surrogate endpoints are infrequently utilized or reported inconsistently as primary outcomes in rehabilitation RCTs. There’s a need for improved reporting quality in rehabilitation RCTs using surrogate endpoints in line with SPIRIT and CONSORT-surrogate checklists.Implications for rehabilitation Randomized controlled trials are key contributors to evidence-based care in the rehabilitation field. Surrogate endpoints are substitutes for target outcomes of interest in randomized controlled trials, such as person-centered outcomes, and are used to improve trial efficiency. Surrogate endpoints are underutilized as primary outcomes and inconsistently reported in rehabilitation randomized controlled trials. Less than 50% of the rehabilitation randomized controlled trials showed compliance with some of the validity items of the CONSORT-surrogate checklists. Rehabilitation professionals should critically assess trials using surrogate endpoints, ensure their validity in predicting patient-relevant outcomes and consider their limitations when interpreting results.