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Competing risks of mortality with marathons: retrospective analysis

BMJ 2007; 335 doi: (Published 20 December 2007) Cite this as: BMJ 2007;335:1275
  1. Donald A Redelmeier, professor of medicine 1,
  2. J Ari Greenwald, resident in emergency medicine 2
  1. 1Department of Medicine, University of Toronto, and Sunnybrook Health Sciences Centre, Ontario, Canada M4N 3M5
  2. 2Department of Medicine, University of Toronto, Toronto, Canada
  1. Correspondence to: D A Redelmeier dar{at}


    Objective To determine from a societal perspective the risk of sudden cardiac death associated with running in an organised marathon compared with the risk of dying from a motor vehicle crash that might otherwise have taken place if the roads had not been closed.

    Design Population based retrospective analysis with linked ecological comparisons of sudden death.

    Setting Marathons with at least 1000 participants that had two decades of history and were on public roads in the United States, 1975-2004.

    Main outcome measures Sudden death attributed to cardiac causes or to motor vehicle trauma.

    Results The marathons provided results for 3 292 268 runners on 750 separate days encompassing about 14 million hours of exercise. There were 26 sudden cardiac deaths observed, equivalent to a rate of 0.8 per 100 000 participants (95% confidence interval 0.5 to 1.1). Because of road closure, an estimated 46 motor vehicle fatalities were prevented, equivalent to a relative risk reduction of 35% (95% confidence interval 17% to 49%). The net reduction in sudden death during marathons amounted to a ratio of about 1.8 crash deaths saved for each case of sudden cardiac death observed (95% confidence interval: 0.7 to 3.8). The net reduction in total deaths could not be explained by re-routing traffic to other regions or days and was consistent across different parts of the country, decades of the century, seasons of the year, days of the week, degree of competition, and course difficulty.

    Conclusion Organised marathons are not associated with an increase in sudden deaths from a societal perspective, contrary to anecdotal impressions fostered by news media.


    • We thank Fred Brenneman, Trevor Hastie, Daniel Hackam, David Juurlink, Marko Katic, Robert Myers, Lee Ross, Michael Schull, Steven Shumak, Arthur Slutsky, Matthew Stanbrook, and Robert Tibshirani for helpful comments on specific points.

    • Contributors: Both authors participated in study design, interpretation of results, and approval of the final draft. DAR is guarantor.

    • Funding: Canada Research Chair in Medical Decision Sciences, the Canadian Institutes of Health Research, the National Institutes of Health Resuscitation Outcomes Consortium, the University of Toronto Summer Scholarship Program, the Patient Safety Service of Sunnybrook Health Sciences Centre, and the PSI Foundation of Ontario.

    • Competing interests: None declared.

    • Ethical approval: Research ethics board of Sunnybrook Health Sciences Centre.

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

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