Author Affiliations: US Cochrane Center and Center for Clinical Trials, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (Dr Dickersin); and Philip R. Lee Institute for Health Policy Studies, University of California, San Francisco (Dr Rennie). Dr Rennie is also Deputy Editor, JAMA.
The original purpose of registries of clinical trials was to reveal the existence of all trials, published or not, to investigators and systematic reviewers. Trials left unpublished because results were unfavorable to their sponsors, or simply because investigators never submitted them to journals for publication, could then be discovered, the trial investigators contacted, and the available trial evidence involving medical interventions could then be assessed. This would help eliminate publication bias, shown originally in the 1980s,1 demonstrated by Simes2 to affect the treatment of patients, and later revealed to be widespread by the expanding efforts of the Cochrane Collaboration. A seemingly arcane statistical point became a pressing clinical problem.
Dickersin K, Rennie D. The Evolution of Trial Registries and Their Use to Assess the Clinical Trial Enterprise. JAMA. 2012;307(17):1861-1864. doi:10.1001/jama.2012.4230