Clinical trial registries: more international, converging efforts are needed

Clinical trial registries are being increasingly acknowledged worldwide. We searched for possibly trustworthy online registries that are not already included in the International Clinical Trials Registry Platform to evaluate whether other useful trial data sources exist and whether they could potentially be consulted, since the strategy search within this platform has recently been questioned. Fifty-nine registries were initially identified, and 11 of them fit the criteria applied and were analyzed for quality and usability. Four additional, potentially reliable registries were identified that researchers could exploit in order to obtain a more global view of the issue being investigated.