Abstract
ObjectiveIn an effort to understand how results of human clinical trials are made public, we analyze a large set of clinical trials registered at ClinicalTrials.gov, the world’s largest clinical trial registry.Materials and MethodsWe considered two trial result artifacts: (1) existence of a trial result journal article that is formally linked to a registered trial or (2) the deposition of a trial’s basic summary results within the registry.ResultsThe study sample consisted of 8907 completed, interventional, phase 2-or-higher clinical trials that were completed in 2006-2009. The majority of trials (72.2%) had no structured trial-article link present. A total of 2367 trials (26.6%) deposited basic summary results within the registry. Of those , 969 trials (10.9%) were classified as trials with extended results and 1398 trials (15.7%) were classified as trials with only required basic results. The majority of the trials (54.8%) had no evidence of results, based on either linked result articles or basic summary results (silent trials), while a minimal number (9.2%) report results through both registry deposition and publication.DiscussionOur study analyzes the body of linked knowledge around clinical trials (which we refer to as the “trialome”). Our results show that most trials do not report results and, for those that do, there is minimal overlap in the types of reporting. We identify several mechanisms by which the linkages between trials and their published results can be increased.ConclusionOur study shows that even when combining publications and registry results, and despite availability of several information channels, trial sponsors do not sufficiently meet the mandate to inform the public either via a linked result publication or basic results submission.
Highlights
The purposes of trial registries, such as ClinicalTrials.gov, include serving as a repository for shared clinical trials results and providing the ability to track journal articles reporting trial results in medical literature
We examined the ClinicalTrials.gov data to identify the presence of trial results
The fact that the ClinicalTrials.gov administrators provide the extended results reporting at least as an option for trial record managers, is a step in the right direction, but it is not mandated by the legislature and, as our results show, not used by the majority of basic results depositors
Summary
The purposes of trial registries, such as ClinicalTrials.gov, include serving as a repository for shared clinical trials results and providing the ability to track journal articles reporting trial results in medical literature. We are interested in exploring mechanisms for automatically identifying results of completed trials that have either shared data sets within the registry or linked the trial records to published, peer-reviewed journal articles. We combined ClinicalTrials.gov data with data from PubMed, the popular citation database from the National Library of Medicine (NLM), to look at a large set of clinical trials and investigate how results of trials are made publicly available. Our study looks at the largest set of registered trials compared with previous publication rate analyses
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