Reporting summary results in clinical trial registries: updated guidance from WHO

The importance of publicly registering clinical trials and reporting their results in registries is widely recognised. While substantial progress has been made with registering trials before enrolment, the availability of results in registries remains uncommon despite expanding legislative and funder requirements—leading to an incomplete evidence base and avoidable waste of resources, particularly for unpublished trials. This paper discusses the rationale for reporting summary results in trial registries, reviews the current landscape of registry policies, and presents new WHO guidance for reporting results in registries. The 2025 WHO guidance was developed after consultation with relevant parties, including researchers, patients, sponsors, funders, regulators, journal editors, registry administrators, and the public. The guidance defines eight minimum items that are essential for understanding and interpreting the summary results for all trials. Implementation of the WHO guidance by trial registries, broad adherence by investigators and sponsors, and endorsement by funders, regulators, legislators, research ethics committees, patient organisations, and journals can help enhance the contribution of trials to scientific knowledge, patient care, and health policy.