Clinical trial registries provide information on what trial results are pending or already available, making them a valuable resource for clinicians and researchers. Multiple trial registries exist, and some clinical trials appear in more than one registry.
While working to link all publicly available information from all clinical trial registries into one open database known as OpenTrials, Jessica Fleminger and Ben Goldacre from the University of Oxford recently identified multiple errors, omissions and discrepancies between different registries.
These inconsistencies prompted the researchers to investigate discrepancies specifically related to trial completion status — whether a trial has wrapped up and if data has been reported or is still being processed. They analyzed 10,492 clinical trials registered on both of two major registries, the EU Clinical Trial Register (EUCTR) and ClinicalTrials.gov.
Fleminger and Goldacre found that 33.9 percent of dual-registered trials listed as “ongoing” on EUCTR are listed as “completed” on ClinicalTrials.gov. According to their report in PLOS ONE, the prevalence of incorrect statuses in trial registries could mean that important data from completed trials may be overlooked by other research, such as systematic reviews or studies looking at publication bias.
While it is unclear whether researchers, registry owners, or both are responsible for the errors, the authors recommend that researchers who find discrepancies request clarifications from the trial organizers. Meanwhile, registry owners should perform simple cross checks of data to ensure that the completion status is accurate.
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Reference: Fleminger J, Goldacre B (2018) Prevalence of clinical trial status discrepancies: A cross-sectional study of 10,492 trials registered on both ClinicalTrials.gov and the European Union Clinical Trials Register. PLoS ONE 13(3): e0193088. https://doi.org/10.1371/journal.pone.0193088