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Original research
Reporting of drug trial funding sources and author financial conflicts of interest in Cochrane and non-Cochrane meta-analyses: a cross-sectional study
  1. Kimberly Turner1,2,
  2. Andrea Carboni-Jiménez1,2,
  3. Carla Benea1,2,
  4. Katharine Elder1,2,
  5. Brooke Levis1,2,
  6. Jill Boruff3,
  7. Michelle Roseman4,
  8. Lisa Bero5,
  9. Joel Lexchin6,
  10. Erick H Turner7,
  11. Andrea Benedetti8,
  12. Brett D Thombs1,2
  1. 1Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
  2. 2McGill University, Montreal, Quebec, Canada
  3. 3Schulich Library of Physical Sciences, Life Sciences, and Engineering, McGill University, Montreal, Quebec, Canada
  4. 4Kingsway Medical Centre Family Health Organization, Toronto, Ontario, Canada
  5. 5Charles Perkins Centre/Pharmacy, University of Sydney, Camperdown, New South Wales, Australia
  6. 6School of Health Policy and Management, York University, Toronto, Ontario, Canada
  7. 7Department of Psychiatry, Oregon Health & Science University, Portland, Oregon, USA
  8. 8Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada
  1. Correspondence to Dr Brett D Thombs; brett.thombs{at}


Objective To (1) investigate the extent to which recently published meta-analyses report trial funding, author–industry financial ties and author–industry employment from included randomised controlled trials (RCTs), comparing Cochrane and non-Cochrane meta-analyses; (2) examine characteristics of meta-analyses independently associated with reporting funding sources of included RCTs; and (3) compare reporting among recently published Cochrane meta-analyses to Cochrane reviews published in 2010.

Design Review of consecutive sample of recently published meta-analyses.

Data sources MEDLINE database via PubMed searched on 19 October 2018.

Eligibility criteria for selecting articles We selected the 250 most recent meta-analyses listed in PubMed that included a documented search of at least one database, statistically combined results from ≥2 RCTs and evaluated the effects of a drug or class of drugs.

Results 90 of 107 (84%) Cochrane meta-analyses reported funding sources for some or all included trials compared with 21 of 143 (15%) non-Cochrane meta-analyses, a difference of 69% (95% CI 59% to 77%). Percent reporting was also higher for Cochrane meta-analyses compared with non-Cochrane meta-analyses for trial author–industry financial ties (44% versus 1%; 95% CI for difference 33% to 52%) and employment (17% versus 1%; 95% CI for difference 9% to 24%). In multivariable analysis, compared with Cochrane meta-analyses, the odds ratio (OR) for reporting trial funding was ≤0.11 for all other journal category and impact factor combinations. Compared with Cochrane reviews from 2010, reporting of funding sources of included RCTs among recently published Cochrane meta-analyses improved by 54% (95% CI 42% to 63%), and reporting of trial author–industry financial ties and employment improved by 37% (95% CI 26% to 47%) and 10% (95% CI 2% to 19%).

Conclusions Reporting of trial funding sources, trial author–industry financial ties and trial author–industry employment in Cochrane meta-analyses has improved since 2010 and is higher than in non-Cochrane meta-analyses.

  • epidemiology
  • statistics & research methods
  • medical ethics

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  • Contributors KT, MR, JB, LB, JL, EHT, AB and BDT were responsible for the study conception and design. KT, AC-J, CB, and KE were responsible for title and abstract and full-text review. KT and AC-J were responsible for data extraction and validation. KT, BL, AB, and BDT analysed and interpreted results. KT and BDT drafted the manuscript. All authors provided a critical review and approved the final manuscript. BDT is the guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests All authors have completed the ICMJE uniform disclosure form at Dr. Bero disclosed that she is Senior Editor, Cochrane Public Health and Health Systems, for which the University of Sydney receives remuneration. Dr. Thombs disclosed that he is a content editor with the Cochrane Common Mental Disorders review group (no remuneration received). All other authors declared: 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.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

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

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. All extracted data are available in the main tables or in online supplementary material. No additional data were extracted.

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