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Mortality of US astronauts: comparisons with professional athletes
  1. Robert J Reynolds,
  2. Steven M Day
  1. Mortality Research & Consulting, City of Industry, California, USA
  1. Correspondence to Dr Robert J Reynolds, Mortality Research & Consulting, Inc, City of Industry CA 91748, USA; rreynolds{at}


Objective Studies of mortality among US astronauts are complicated by the healthy worker effect, which predicts lower mortality for astronauts than the general population based solely on the ability to become and remain an astronaut. We attempt to evaluate astronaut mortality risk while accounting for the healthy worker effect.

Methods We compare mortality rates of male US astronauts with those of professional athletes from Major League Baseball and the National Basketball Association between January 1, 1960 and May 31, 2018.

Results Both athlete cohorts and astronauts had significantly lower-than-expected mortality in comparison with the general population. For the overall study period, there were no significant differences in all-cause mortality rates between astronauts and athletes. Astronauts were at greater risk of death from external causes (SMR=583; 95% CI 377 to 860) and reduced risk of death from cardiovascular disease (SMR=39; 95% CI 18 to 73) and all natural causes (SMR=67; 95% CI 47 to 93).

Conclusions The data presented here do not support increased mortality for astronauts due to unique exposures received in space. The mortality experience of astronauts as compared with professional baseball and basketball players should be re-examined periodically as part of the ongoing surveillance of astronaut mortality in years to come.

  • healthy worker effect
  • cardiovascular disease
  • cancer
  • death
  • astronaut

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  • Patient consent for publication Not required.

  • Contributors RJR contributed to study conception, analysis and manuscript preparation. SMD contributed to analysis and manuscript preparation.

  • 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 None declared.

  • Ethics approval The study used a combination of freely available information on public figures obtained on the internet and death data from the National Death Index. The NDI data were obtained under a study protocol which was reviewed by Solutions IRB, an independent institutional review board. Because the protocol represented minimal risk for study subjects and no study subject would be contacted, the protocol was determined to be exempt from the Regulations for the Protection of Human Subjects (45 CFR 46).

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

  • Data sharing statement Data are available from the authors by request and publicly online from the sources listed.