Trial registries are important sources of information for clinicians and researchers, since they provide information on what trial results are pending or already available. While building OpenTrials, an open database that aims to link all publicly available information from all clinical trial registries, the authors of this study identified multiple errors, omissions and discrepancies between different registries. These differences prompted the researchers to investigate the prevalence of incorrect completion statuses between two major registries, the EU Clinical Trials Register (EUCTR) and ClinicalTrials.gov.
The researchers analyzed 10,492 clinical trials that were registered on both ClinicalTrials.gov and EUCTR, examining their trial completion status and reporting status for discrepancies. They found that 16.2% of dual registered trials had discrepant completion statuses and 33.9% of dual-registered trials listed as 'ongoing' on EUCTR were listed as 'completed' on ClinicalTrials.gov.
The researchers suggest that the prevalence of incorrect statuses on trial entries could mean that they are excluded from studies looking at publication bias or systematic reviews pooling together clinical data from different clinical trials. While it is unclear whether researchers, registry owners, or both are responsible for the errors, the authors recommend that researchers identifying discrepancies should request clarifications from the trialists, and registry owners should undertake simple cross-checks of data to ensure that the completion status is accurate.
"Trial registries are important public documents: doctors, researchers, and patients rely on the information that trialists post about their clinical trial," says Ben Goldacre. "Concerningly, we now show that this data is commonly inaccurate."
Jessica Fleminger, Ben Goldacre.
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. doi: 10.1371/journal.pone.0193088.