Study title

Randomised controlled trials commonly use surrogate endpoints to substitute for a target outcome (outcome of direct interest and relevance to trial participants, clinicians, and other stakeholders, e.g., all-cause mortality) to improve their efficiency, (through shorter trial duration, reduced sample size, and thus lower research costs), ethical or practical reasons. However, a consequence of reliance on surrogate endpoints is the increase of the uncertainty of an intervention’s treatment effect and potential failure to provide adequate information on intervention harms. This has led to calls for improved reporting of trials using surrogate endpoints. This project aimed to develop consensus-driven reporting guidelines for protocols and trial reports using surrogate endpoints as the primary outcome(s): SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) extension checklist: SPIRIT-Surrogate; and CONSORT (Consolidated Standards of Reporting Trials) extension checklist: CONSORT-Surrogate. The extensions were developed using four phases: literature reviews to identify potential items for reporting (searches up to May 27th 2022); Delphi survey (to rate potential items by a multidisciplinary group of stakeholders) conducted between August 24th to December 11th 2022; consensus meeting (to finalise checklist items) held on March 13-14th , 2023; and knowledge translation (piloting of checklist). The SPIRIT-Surrogate extension includes nine items modified from the SPIRIT 2013 checklist. The extension includes nine items modified from the CONSORT 2010 checklist and two new items.Randomised controlled trials commonly use surrogate endpoints to substitute for a target outcome (outcome of direct interest and relevance to trial participants, clinicians, and other stakeholders, e.g., all-cause mortality) to improve their efficiency, (through shorter trial duration, reduced sample size, and thus lower research costs), ethical or practical reasons....