Accounting for cross-registration in monitoring responsible research in clinical trials: A cross-sectional study of trials at German university medical centers

BackgroundIdentifying and monitoring clinical trials is crucial for responsible research systems and is relevant to all stakeholders in clinical research. Trial registries support accountability and transparency by providing a publicly available and rich source of information on trials. Cross-registration, where the same trial is registered in more than one registry, can complicate efforts to study the clinical research enterprise. Duplicate entries may need to be de-duplicated or merged, and discrepancies across registrations may affect conclusions about trial adherence to registration and reporting standards. MethodsWe identified and characterized cross-registrations in an existing dataset of 2,895 trials conducted at German university medical centers and registered on ClinicalTrials.gov or the German Clinical Trials Register. We focused on cross-registrations on the EU Clinical Trials Register (EUCTR), given the legal basis of registration and reporting in this registry. We manually validated a sample of EUCTR cross-registrations, and assessed discrepancies in key information across registrations of the same trial. ResultsWe identified 625 potential EUCTR cross-registrations. The majority of potential cross-registrations (75%, n = 470) were linked through a Trial Registration Number (TRN) in at least one of the registries. Only 17% (n = 109) were linked through a TRN in both registries. Title matching and TRNs in trial results publications led to an additional 155 (25%) potential cross-registrations. For manually validated EUCTR cross-registrations (n = 228), we found discrepancies in the registration status, recruitment status, completion date, and availability of summary results across registration of the same trial. ConclusionUnambiguous identification of trials and consistent trial records are essential to support the inclusion of relevant trials in systematic reviews, and for monitoring responsible research. Yet, registrations of the same trial are often inadequately linked and present discrepant information. Our findings suggest the need for additional guidance and coordination on cross-registration across stakeholders.