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Research Letter
February 2015

Association of Cardiovascular Trial Registration With Positive Study Findings: Epidemiological Study of Randomized Trials (ESORT)

Author Affiliations
  • 1George Institute for Global Health, University of Oxford, Oxford, England
  • 2Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences, University of Oxford, Oxford, England
  • 3Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 4University of Oxford, Oxford, England
  • 5Centre d'Epidémiologie Clinique, Université Paris Descartes, INSERM U1153, Paris, France
JAMA Intern Med. 2015;175(2):304-307. doi:10.1001/jamainternmed.2014.6924

Trial registration has been proposed to reduce selective publication and outcome reporting, thereby increasing accountability in the conduct of research.1 Since 2005, policy makers, journal editors, and research funders have increasingly endorsed and mandated trial registration.2 However, evidence to support the proposed benefits of trial registration is lacking. Analysis of a select group of randomized trials (RTs) in oncology found that registered and unregistered trials were equally likely to reach conclusions favoring new oncology drugs.3 We conducted a cross-sectional analysis of published cardiovascular RTs to compare RTs reported as registered with those not reported as registered.

An RT was eligible for analysis if it was published on PubMed in December 2012 and focused on a cardiovascular disease, as defined by the International Classification of Diseases. Our research group4 has previously reported a detailed description of the process. Briefly, 2 reviewers independently screened all abstracts and full texts. No language restrictions were applied. Study characteristics and methodological characteristics (Table 1) were extracted in duplicate. The International Committee of Medical Journal Editors definition of trial registration was used.1 The primary outcome was the reported study findings for each trial, categorized as significant positive, nonsignificant, or significant negative. Trials not reported as registered were searched for registry information using the World Health Organization Trials Registry Platform. The χ2 test, Fisher exact test, and Wilcoxon rank-sum test were applied as appropriate for analysis.