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Original research
State of the evidence: a survey of global disparities in clinical trials
  1. Iain James Marshall1,
  2. Veline L'Esperance1,
  3. Rachel Marshall2,
  4. James Thomas3,
  5. Anna Noel-Storr4,
  6. Frank Soboczenski1,
  7. Benjamin Nye5,
  8. Ani Nenkova6,
  9. Byron C Wallace5
  1. 1School of Population Health and Environmental Sciences, King's College London, London, UK
  2. 2Editorial and Methods Department, Cochrane, London, UK
  3. 3EPPI-Centre, Department of Social Science, UCL, London, UK
  4. 4Cochrane Dementia Group, University of Oxford, Oxford, UK
  5. 5Khoury College of Computer Sciences, Northeastern University, Boston, Massachusetts, USA
  6. 6Computer and Information Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
  1. Correspondence to Dr Iain James Marshall; iain.marshall{at}kcl.ac.uk

Abstract

Introduction Ideally, health conditions causing the greatest global disease burden should attract increased research attention. We conducted a comprehensive global study investigating the number of randomised controlled trials (RCTs) published on different health conditions, and how this compares with the global disease burden that they impose.

Methods We use machine learning to monitor PubMed daily, and find and analyse RCT reports. We assessed RCTs investigating the leading causes of morbidity and mortality from the Global Burden of Disease study. Using regression models, we compared numbers of actual RCTs in different health conditions to numbers predicted from their global disease burden (disability-adjusted life years (DALYs)). We investigated whether RCT numbers differed for conditions disproportionately affecting countries with lower socioeconomic development.

Results We estimate 463 000 articles describing RCTs (95% prediction interval 439 000 to 485 000) were published from 1990 to July 2020. RCTs recruited a median of 72 participants (IQR 32–195). 82% of RCTs were conducted by researchers in the top fifth of countries by socio-economic development. As DALYs increased for a particular health condition by 10%, the number of RCTs in the same year increased by 5% (3.2%–6.9%), but the association was weak (adjusted R2=0.13). Conditions disproportionately affecting countries with lower socioeconomic development, including respiratory infections and tuberculosis (7000 RCTs below predicted) and enteric infections (9700 RCTs below predicted), appear relatively under-researched for their disease burden. Each 10% shift in DALYs towards countries with low and middle socioeconomic development was associated with a 4% reduction in RCTs (3.7%–4.9%). These disparities have not changed substantially over time.

Conclusion Research priorities are not well optimised to reduce the global burden of disease. Most RCTs are produced by highly developed countries, and the health needs of these countries have been, on average, favoured.

  • randomised control trial
  • geographic information systems
https://creativecommons.org/licenses/by/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

https://doi.org/10.1136/bmjgh-2020-004145

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    Footnotes

    • Handling editor Seye Abimbola

    • Twitter @ijmarshall

    • Contributors Initial study conceived by IJM and BCW, with intellectual input from all authors. Automatic information extraction system created by: IJM, BCW, BN, AN and FS. Curation of data for training machine learning models: JT, AN-S, BCW, BN, AN and IJM. Statistical analysis designed and conducted by IJM, VL and BCW. Initial draft of manuscript by IJM and BCW. Critical revisions for important intellectual content: all; Approval of final manuscript: all.

    • Funding This work is funded by the UK Medical Research Council (MRC), through its Skills Development Fellowship programme (IJM), MR/N015185/1, and the US National Institutes of Health (NIH) under the National Library of Medicine, 2R01-LM012086-05 (IJM, FS and BCW). VL is funded by a National Institute for Health Research (NIHR), (Doctoral Research Fellow- DRF-2017-10-13). JT received grants from Cochrane during the conduct of the study.

    • Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

    • Map disclaimer The depiction of boundaries on this map does not imply the expression of any opinion whatsoever on the part of BMJ (or any member of its group) concerning the legal status of any country, territory, jurisdiction or area or of its authorities. This map is provided without any warranty of any kind, either express or implied.

    • Competing interests None declared.

    • 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 Data are available in a public, open access repository. All data are available in a public, open access repository (DOI 10.17605/osf.io/3db76).