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Comment & Response
July 3, 2018

Professional Football Participation and Mortality—Reply

Author Affiliations
  • 1Department of Medical Ethics and Health Policy, University of Pennsylvania, Philadelphia
  • 2Department of Heart and Vascular (Cardiology), Everett Clinic, Everett, Washington
  • 3Department of Health Care Policy, Harvard Medical School, Boston, Massachusetts
JAMA. 2018;320(1):92-93. doi:10.1001/jama.2018.6717

In Reply We agree with Drs Smith and Siddiqi that the estimated mortality hazard may be clinically meaningful, but because it is based on a small number of deaths, further follow-up is necessary. We would encourage this interpretation even if the P value had fallen below .05.

Both letters question our choice of comparison group, but this choice should be viewed in the context of the prior literature, which used general population controls. Professional football players have higher levels of physical fitness and tend to abstain from unhealthy behaviors compared with individuals in the general population.1,2 The skill and ability to succeed in professional football are likely negatively correlated with baseline mortality risk. We believed that this healthy worker bias3 was substantial,4 likely explaining why prior studies demonstrated substantially lower mortality risks of NFL players relative to general population controls.5 We focused on replacement players because we believed these athletes—by virtue of being on the margin of making an NFL roster—had baseline risk factors that were more similar to NFL players than general population controls. We could not test this assumption because this was a historical case study and collecting baseline health data was infeasible. Nevertheless, our findings were consistent with this contention. We found higher estimated mortality risk among career NFL players, opposite to the conclusion of prior studies.