A patient can live longer, feel better, or function better—these are direct, patient relevant clinical outcomes.1 Surrogate endpoints, in contrast, are indirect measures intended to predict such benefits. They can be used to shorten the duration of trials and make treatments available sooner, but that comes at the cost of greater uncertainty: improving a surrogate may not improve what ultimately matters to patients.A linked article by Lo and colleagues (doi:10.1136/bmj-2026-100618) presents the REASSurE framework for evaluating a single surrogate against a clinical endpoint.2 Developed through a Delphi survey, consensus meeting, piloting, and finalisation, the framework deserves credit for its transparent methods and reporting. It provides a structured checklist of mandatory or recommended items across four areas. Joint evaluation of multiple surrogates remains outside its scope.REASSurE aims to go beyond existing approaches, including the IQWiG (Institute for Quality and Efficiency in Health Care) framework,3 the Biomarker-Surrogacy Evaluation Schema,4 and the three-level…
