Surrogate endpoints in trials: a call for better reporting.

Using a surrogate endpoint as a substitute for a patient-relevant final outcome enables randomised controlled trials (RCTs) to be conducted more efficiently. However, the use of surrogates remains controversial and there is currently no guideline for the reporting of RCTs using surrogate endpoints; therefore, we seek to develop SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) extensions to improve the reporting of these trials. We would like to invite interested individuals (trial methodologists, journal editors, healthcare industry, regulators and payers, and patient/public representative groups), particularly those with experience in the use of surrogate endpoints in trials.