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Characteristics and publication fate of unregistered and retrospectively registered clinical trials submitted to The BMJ over 4 years
  1. Elizabeth Loder1,2,
  2. Stephen Loder3,
  3. Sophie Cook1
  1. 1 Editorial Department, The BMJ, London, UK
  2. 2 Department of Neurology, Brigham and Women’s Faulkner Hospital, Boston, Massachusetts, USA
  3. 3 Post-baccalaureate Premedical Program, Columbia University, New York, New York, USA
  1. Correspondence to Stephen Loder; scl963{at}


Objectives We sought to evaluate the characteristics and publication fate of improperly registered clinical trials submitted to a medical journal (The BMJ) over a 4-year period to identify common types of registration issues and their relation to publication outcomes.

Design Research articles submitted to The BMJ and identified as unregistered or retrospectively registered by editors were included if they reported outcomes of a clinical trial. Relevant data regarding the trials were then extracted from each paper. Trials were categorised as prospectively registered, registered in an unapproved registry, unregistered or other, and explanations for registration deficiencies were grouped into six categories. We searched PubMed and Google to determine whether, where and when improperly registered studies were subsequently published and whether registration issues were disclosed.

Results 123 research papers reporting apparently unregistered or retrospectively registered clinical trials were identified. 110 studies (89.4%) were retrospectively registered, nine (7.3%) were unregistered, three (2.4%) had been registered in an unapproved registry and one study originally lacking registration details was later discovered to have been prospectively registered. 82 studies (66.6%) were funded entirely or in part by government sources, and only seven studies (5.7%) received funding from industry. Of those papers submitted to The BMJ through the end of 2015, 67 of the 70 papers rejected for registration problems (95.7%) were subsequently published in another journal. The registration problem was disclosed in only 2 (2.9%).

Conclusions Improper registration remains a problem, particularly for clinical trials that are government or foundation-funded. Nonetheless, improperly registered trials are almost always published, suggesting that medical journal editors may not actively enforce registration requirements.

  • journalology
  • clinical trial registration
  • medical publishing

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  • Contributors EL conceived the idea for the study, obtained, recorded, analysed and organised the data, wrote the first draft of the paper and was a major contributor in revising the manuscript. SL participated in obtaining, organising, analysing and interpreting data, created the figure, formatted tables and edited the final version of the manuscript. SC independently checked and verified a portion of the data, analysed and interpreted data and was a major contributor in revising the manuscript. All authors read and approved the final manuscript.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests EL has an academic interest in trial registration and research integrity and has published on the topic. EL and SC are research editors for The BMJ, which is a well-recognised proponent of trial registration. The BMJ is a founding member of the ICMJE and was involved in the development of requirements for clinical trial registration as a condition of publication.

  • Patient consent Not required.

  • Ethics approval The data used in this study were part of an internal BMJ audit of author adherence to trial registration requirements. Authors are informed upon submission of a research paper that The BMJ routinely conducts audits of papers submitted to the journal and that their paper may be included.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data are available. All deidentified data supporting the conclusions of the paper are included in this published article (and its online supplementary appendix).