IDEAS home Printed from https://ideas.repec.org/a/plo/pone00/0021248.html
   My bibliography  Save this article

Potential Misinterpretation of Treatment Effects Due to Use of Odds Ratios and Logistic Regression in Randomized Controlled Trials

Author

Listed:
  • Mirjam J Knol
  • Ruben G Duijnhoven
  • Diederick E Grobbee
  • Karel G M Moons
  • Rolf H H Groenwold

Abstract

Background: In randomized controlled trials (RCTs), the odds ratio (OR) can substantially overestimate the risk ratio (RR) if the incidence of the outcome is over 10%. This study determined the frequency of use of ORs, the frequency of overestimation of the OR as compared with its accompanying RR in published RCTs, and we assessed how often regression models that calculate RRs were used. Methods: We included 288 RCTs published in 2008 in five major general medical journals (Annals of Internal Medicine, British Medical Journal, Journal of the American Medical Association, Lancet, New England Journal of Medicine). If an OR was reported, we calculated the corresponding RR, and we calculated the percentage of overestimation by using the formula . Results: Of 193 RCTs with a dichotomous primary outcome, 24 (12.4%) presented a crude and/or adjusted OR for the primary outcome. In five RCTs (2.6%), the OR differed more than 100% from its accompanying RR on the log scale. Forty-one of all included RCTs (n = 288; 14.2%) presented ORs for other outcomes, or for subgroup analyses. Nineteen of these RCTs (6.6%) had at least one OR that deviated more than 100% from its accompanying RR on the log scale. Of 53 RCTs that adjusted for baseline variables, 15 used logistic regression. Alternative methods to estimate RRs were only used in four RCTs. Conclusion: ORs and logistic regression are often used in RCTs and in many articles the OR did not approximate the RR. Although the authors did not explicitly misinterpret these ORs as RRs, misinterpretation by readers can seriously affect treatment decisions and policy making.

Suggested Citation

  • Mirjam J Knol & Ruben G Duijnhoven & Diederick E Grobbee & Karel G M Moons & Rolf H H Groenwold, 2011. "Potential Misinterpretation of Treatment Effects Due to Use of Odds Ratios and Logistic Regression in Randomized Controlled Trials," PLOS ONE, Public Library of Science, vol. 6(6), pages 1-5, June.
    • Handle: RePEc:plo:pone00:0021248
    DOI: 10.1371/journal.pone.0021248
    as

    Download full text from publisher

    File URL: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021248
    Download Restriction: no
    File URL: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0021248&type=printable
    Download Restriction: no
    File URL: https://libkey.io/10.1371/journal.pone.0021248?utm_source=ideas
    LibKey link: if access is restricted and if your library uses this service, LibKey will redirect you to where you can use your library subscription to access this item
    ---><---

    Citations

    Citations are extracted by the CitEc Project, subscribe to its RSS feed for this item.
    as


    Cited by:

    1. Tyler J. VanderWeele, 2020. "Optimal approximate conversions of odds ratios and hazard ratios to risk ratios," Biometrics, The International Biometric Society, vol. 76(3), pages 746-752, September.
    2. Fleur E P van Dooren & Giesje Nefs & Miranda T Schram & Frans R J Verhey & Johan Denollet & François Pouwer, 2013. "Depression and Risk of Mortality in People with Diabetes Mellitus: A Systematic Review and Meta-Analysis," PLOS ONE, Public Library of Science, vol. 8(3), pages 1-11, March.
    3. Riutort Sebastià & Julià Albert & Laín Bru, 2023. "Basic Income at Municipal Level: Insights from the Barcelona B-MINCOME Pilot," Basic Income Studies, De Gruyter, vol. 18(1), pages 1-30, June.

    More about this item

    Statistics

    Access and download statistics

    Corrections

    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:plo:pone00:0021248. See general information about how to correct material in RePEc.

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    We have no bibliographic references for this item. You can help adding them by using this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: plosone (email available below). General contact details of provider: https://journals.plos.org/plosone/ .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.