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Informed consent in pragmatic trials: results from a survey of trials published 2014–2019
  1. Jennifer Zhe Zhang1,
  2. Stuart G Nicholls2,
  3. Kelly Carroll2,
  4. Hayden Peter Nix3,
  5. Cory E Goldstein4,
  6. Spencer Phillips Hey5,
  7. Jamie C Brehaut1,2,
  8. Paul C McLean6,
  9. Charles Weijer7,
  10. Dean A Fergusson1,2,8,
  11. Monica Taljaard1,2
  1. 1 School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
  2. 2 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  3. 3 Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
  4. 4 Philosophy, Rotman Institute of Philosophy, London, Ontario, Canada
  5. 5 Center for Bioethics, Harvard Medical School, Boston, Massachusetts, USA
  6. 6 Boston, Massachusetts, USA
  7. 7 Medicine, Epidemiology and Biostatistics, and Philosophy, Western University, London, Ontario, Canada
  8. 8 Medicine, University of Ottawa, Ottawa, Ontario, Canada
  1. Correspondence to Dr Monica Taljaard, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1N 6N5, Canada; mtaljaard{at}


Objectives To describe reporting of informed consent in pragmatic trials, justifications for waivers of consent and reporting of alternative approaches to standard written consent. To identify factors associated with (1) not reporting and (2) not obtaining consent.

Methods Survey of primary trial reports, published 2014–2019, identified using an electronic search filter for pragmatic trials implemented in MEDLINE, and registered in

Results Among 1988 trials, 132 (6.6%) did not include a statement about participant consent, 1691 (85.0%) reported consent had been obtained, 139 (7.0%) reported a waiver and 26 (1.3%) reported consent for one aspect (eg, data collection) but a waiver for another (eg, intervention). Of the 165 trials reporting a waiver, 76 (46.1%) provided a justification. Few (53, 2.9%) explicitly reported use of alternative approaches to consent. In multivariable logistic regression analyses, lower journal impact factor (p=0.001) and cluster randomisation (p<0.0001) were significantly associated with not reporting on consent, while trial recency, cluster randomisation, higher-income country settings, health services research and explicit labelling as pragmatic were significantly associated with not obtaining consent (all p<0.0001).

Discussion Not obtaining consent seems to be increasing and is associated with the use of cluster randomisation and pragmatic aims, but neither cluster randomisation nor pragmatism are currently accepted justifications for waivers of consent. Rather than considering either standard written informed consent or waivers of consent, researchers and research ethics committees could consider alternative consent approaches that may facilitate the conduct of pragmatic trials while preserving patient autonomy and the public’s trust in research.

  • clinical trial
  • ethics- research
  • primary health care
  • informed consent
  • ethics committees

Data availability statement

No data are available.

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  • Twitter @StuartGNicholl1, @HaydenPNix, @coryegoldstein, @SpencerPHey, @paulcmclean, @charlesweijer

  • Contributors This study was conceived by MT and DAF. CEG, SPH, JCB, CW, DAF and MT contributed to acquisition of funding. All authors contributed to the development of the data extraction form. JZZ, MT, SGN, KC and HPN extracted data. SPH contributed to database management. JZZ conducted the statistical analysis under the supervision of MT. JZZ and MT wrote the first draft of the manuscript. All authors contributed to critical review of the manuscript. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. MT is the guarantor.

  • Funding This work is supported by the Canadian Institutes of Health Research through the Project Grant competition (competitive, peer-reviewed), award number PJT-153045). MT and SPH are funded by the National Institute of Aging (NIA) of the National Institutes of Health under Award Number U54AG063546, which funds NIA Imbedded Pragmatic Alzheimer’s Disease and AD-Related Dementias Clinical Trials Collaboratory (NIA IMPACT Collaboratory).

  • Disclaimer The funders had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.

  • Competing interests CW receives consulting income from Cardialen, Eli Lilly & Company, and Research Triangle Institute International. Other authors report no support from any organisation for the submitted work; 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.

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

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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