Bias in reporting results of scientific studies has been a significant problem in basic and clinical science. The lack of publication of results of trials can lead to unnecessary duplication. Results of studies reported in the peer reviewed literature may only report some of the outcomes measured or may omit the pre-specified primary outcome if the result was not statistically significant. There have been many initiatives and new regulations to encourage prospective registration of studies in clinicaltrials.gov, including a proposed rule issued in November of 2014. For all of these reasons, clinicaltrials.gov is becoming an increasingly important resource to ensure inclusion of all relevant studies and information about studies in systematic review.
Despite the potential importance of clinicaltrials.gov for systematic review, there are several barriers to using the system. Searching clinicaltrials.gov for relevant trials can be difficult and time-consuming. And when results published on clinicaltrials.gov do not match information in the peer reviewed literature, it is not clear which source is more accurate.
The EPC Methods Guide recognizes the importance of clinicaltrials.gov and other prospective trial registries and states the following:
- Reviewers should always search ClinicalTrials.gov and the International Clinical Trials Registry Platform for trials that began recruitment after 2005.
- Match trials with publications found from the standard search, noting (1) trials with existing publication, and (2) trials for which no publication was found.
- Construct a table that provides information on trials found in the registry, their publication status, and whether they are completed or currently active trials, and provide a count of the number of unique trials found along with their status at the time of the search.
In these supplements to currently ongoing EPC reports, the process of incorporating information from clinicaltrials.gov into EPC reports will be investigated.
EPC topics included in this project
- Preventing Complications and Treating Symptoms of Diabetic Peripheral Neuropathy
- Management of Infertility
- Omega-3 Fatty Acids and Cardiovascular Disease
- Strategies to Improve Mental Health Care for Children and Adolescents
- Tympanostomy Tubes