Comparison of serious adverse events posted at ClinicalTrials.gov and published in corresponding journal articles

The reporting of serious adverse events (SAEs) in clinical trials is crucial to assess the balance between benefits and risks. For trials with serious adverse events posted at ClinicalTrials.gov, we assessed the consistency between SAEs posted at ClinicalTrials.gov and those published in corresponding journal articles.

All records from ClinicalTrials.gov up to February 2014 were automatically exported in XML format. Among these, we identified all phase III or IV randomized controlled trials with at least one SAE posted. For a random sample of 300 of these trials, we searched for corresponding publications using MEDLINE via PubMed and extracted safety results from the articles.

Among the sample of 300 trials with SAEs posted at ClinicalTrials.gov, 78 (26%) did not have a corresponding publication, and 20 (7%) had a publication that did not match the ClinicalTrials.gov record. For the 202 remaining trials, 26 published articles (13%) did not mention SAEs, 4 (2%) reported no SAEs, and 33 (16%) did not report the total number of SAEs per treatment group. Among the remaining 139 trials, for 44 (32%), the number of SAEs per group published did not match those posted at ClinicalTrials.gov. For 31 trials, the number of SAEs was greater at ClinicalTrials.gov than in the published article, with a difference ≥30 % for at least one group for 21. Only 33 trials (11%) had a publication reporting matching numbers of SAE and describing the type of SAE.

Many trials with SAEs posted at ClinicalTrials.gov are not yet published, omit the reporting of these SAEs in corresponding publications, or report a discrepant number of SAEs as compared with ClinicalTrials.gov. These results underline the need to consult ClinicalTrials.gov for more information on serious harms.