Clinical trial results are almost always listed in government sources, but many never make it into published literature, where they would have much greater exposure. The authors of a new research letter, published in JAMA Internal Medicine, noted that the exclusion of certain clinical trial results, which provide scientific data on a drug, leaves “a distorted body of public evidence.”
In order to assess the availability of clinical trial results in the public domain, researchers evaluated the availability of results in PubMed-cited publications and/or results posted in Clinicaltrials.gov.
The study consisted of 329 trials studying 86 drugs and representing 96 unique sponsor-drug-condition trial sets.
The results found that Clinicaltrials.gov consisted of nearly one-quarter of sampled drug trials and more than one-tenth of sampled sponsor-drug-condition trial sets. However, results remain unavailable in Clinicaltrials.gov or PubMed 7 or more years after study completion for nearly one-quarter of sampled drug trials and more than one-tenth of sampled sponsor-drug-condition trial sets.
“Systematic reviewers who rely entirely on literature searches are at risk of missing relevant evidence,” the authors wrote.