Clinical trial design and dissemination: comprehensive analysis of and PubMed data since 2005

BMJ. 2018 Jun 6:361:k2130. doi: 10.1136/bmj.k2130.


Objective: To investigate the distribution, design characteristics, and dissemination of clinical trials by funding organisation and medical specialty.

Design: Cross sectional descriptive analysis.

Data sources: Trial protocol information from, metadata of journal articles in which trial results were published (PubMed), and quality metrics of associated journals from SCImago Journal and Country Rank database.

Selection criteria: All 45 620 clinical trials evaluating small molecule therapeutics, biological drugs, adjuvants, and vaccines, completed after January 2006 and before July 2015, including randomised controlled trials and non-randomised studies across all clinical phases.

Results: Industry was more likely than non-profit funders to fund large international randomised controlled trials, although methodological differences have been decreasing with time. Among 27 835 completed efficacy trials (phase II-IV), 15 084 (54.2%) had disclosed their findings publicly. Industry was more likely than non-profit trial funders to disseminate trial results (59.3% (10 444/17 627) v 45.3% (4555/10 066)), and large drug companies had higher disclosure rates than small ones (66.7% (7681/11 508) v 45.2% (2763/6119)). Trials funded by the National Institutes of Health (NIH) were disseminated more often than those of other non-profit institutions (60.0% (1451/2417) v 40.6% (3104/7649)). Results of studies funded by large drug companies and NIH were more likely to appear on than were those from non-profit funders, which were published mainly as journal articles. Trials reporting the use of randomisation were more likely than non-randomised studies to be published in a journal article (6895/19 711 (34.9%) v 1408/7748 (18.2%)), and journal publication rates varied across disease areas, ranging from 42% for autoimmune diseases to 20% for oncology.

Conclusions: Trial design and dissemination of results vary substantially depending on the type and size of funding institution as well as the disease area under study.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Clinical Trials as Topic / statistics & numerical data*
  • Cross-Sectional Studies
  • Disclosure / statistics & numerical data*
  • Drug Industry / statistics & numerical data
  • Humans
  • Information Dissemination
  • PubMed
  • Public Sector / statistics & numerical data
  • Randomized Controlled Trials as Topic / economics
  • Randomized Controlled Trials as Topic / statistics & numerical data
  • Registries
  • Research Design / statistics & numerical data*
  • Research Report
  • Research Support as Topic*