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  3. Non-publication of large randomized clinical trials: cross sectional analysis
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Research

Non-publication of large randomized clinical trials: cross sectional analysis

BMJ 2013; 347 doi: https://doi.org/10.1136/bmj.f6104 (Published 29 October 2013) Cite this as: BMJ 2013;347:f6104
  1. Christopher W Jones, attending physician1,
  2. Lara Handler, school of medicine liaison librarian2,
  3. Karen E Crowell, clinical information specialist2,
  4. Lukas G Keil, research assistant3,
  5. Mark A Weaver, assistant professor4,
  6. Timothy F Platts-Mills, assistant professor3
  1. 1Department of Emergency Medicine, Cooper Medical School of Rowan University, OneCooper Plaza, Camden, NJ 08103, USA
  2. 2Health Sciences Library, University of North Carolina Chapel Hill, USA
  3. 3Department of Emergency Medicine, University of North Carolina Chapel Hill, USA
  4. 4Department of Biostatistics, University of North Carolina Chapel Hill, USA
  1. Correspondence to: C W Jones cjones.unc{at}gmail.com
  • Accepted 24 September 2013

Abstract

Objective To estimate the frequency with which results of large randomized clinical trials registered with ClinicalTrials.gov are not available to the public.

Design Cross sectional analysis

Setting Trials with at least 500 participants that were prospectively registered with ClinicalTrials.gov and completed prior to January 2009.

Data sources PubMed, Google Scholar, and Embase were searched to identify published manuscripts containing trial results. The final literature search occurred in November 2012. Registry entries for unpublished trials were reviewed to determine whether results for these studies were available in the ClinicalTrials.gov results database.

Main outcome measures The frequency of non-publication of trial results and, among unpublished studies, the frequency with which results are unavailable in the ClinicalTrials.gov database.

Results Of 585 registered trials, 171 (29%) remained unpublished. These 171 unpublished trials had an estimated total enrollment of 299 763 study participants. The median time between study completion and the final literature search was 60 months for unpublished trials. Non-publication was more common among trials that received industry funding (150/468, 32%) than those that did not (21/117, 18%), P=0.003. Of the 171 unpublished trials, 133 (78%) had no results available in ClinicalTrials.gov.

Conclusions Among this group of large clinical trials, non-publication of results was common and the availability of results in the ClinicalTrials.gov database was limited. A substantial number of study participants were exposed to the risks of trial participation without the societal benefits that accompany the dissemination of trial results.

Footnotes

  • Contributors: CWJ and TPM conceived and designed this study. CWJ, LH, KEC, and LGK acquired the data. CWJ, MAW, and TPM analysed and interpreted the data. MAW provided statistical expertise. The initial manuscript was drafted by CWJ and LGK; all authors contributed to subsequent revisions. CWJ takes responsibility for the overall integrity of the data and the accuracy of the data analysis. CWJ is the guarantor.

  • Funding: MAW is supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences through Grant UL1TR000083. TPM is supported by the National Center for Research Resources through Grant KL2 TR00084. These sponsors had no role in the study design, data collection, data analysis, data interpretation, or manuscript preparation. The corresponding author had full access to all the study data and had final responsibility for the decision to submit the manuscript for publication.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Not required.

  • Data sharing: The dataset is available from the corresponding author at cjones.unc{at}gmail.com.

  • Transparency: The lead author affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/.

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