Repetitive Head Impacts Increases the Hazard of Death Among NFL Players

NFL football
NFL football
Researchers assessed whether exposure to repetitive head impacts during a professional football career was associated with an increased in the risk for all-cause mortality.

Increasing repetitive head impacts are associated with an increased hazard of death among professional football players in the National Football League (NFL), a study in the JAMA Network Open suggests.

The study was a retrospective review of all-cause mortality data from 14,366 football players during the 1969 to 2017 NFL seasons. Only data up to July 1, 2018, were included in this analysis. Pro Football Reference records were used to identify the number of seasons and games played by participants. The exposure of interest was the professional football cumulative head impact index (pfCHII), which was calculated for 13,912 NFL players. The pfCHII, which quantified the amount and severity of repetitive head impacts, combined the reported football history with helmet accelerometer studies in professional players.

A total of 763 of the 14,366 players in the initial cohort (5.3%) had died over the follow-up period. The median pfCHII among the 13,912 players in the pfCHII analysis was 32.63 (interquartile range, 13.71-66.12). The pfCHII scores ranged from 14.18 for wide receivers to 84.34 for offensive linemen. For every 1-log increase in pfCHII, there was a significant increase in the hazard of death for the 1969 to 2017 football seasons (hazard ratio [HR], 2.02; 95% CI, 1.21-3.37; P =.01). Additionally, the quadratic pfCHII was significant for the hazard of death during this period (HR, 0.91; 95% CI, 0.85-0.98; P =.01).

Limitations of this study included the variability in measurements of repetitive head impacts across the specified seasons, the inability to adjust for race/ethnicity, and the inclusion of only professional football players vs players who participated in college, high school, or youth football programs.

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The investigators of this study suggest that the “reduction in repetitive head impacts from playing football or other activities through additional rule and equipment changes may be associated with reduced mortality.”


Kmush BL, Mackowski M, Ehrlich J, Walia B, Owora A, Sanders S. Association of professional football cumulative head impact index scores with all-cause mortality among national football league players. JAMA Netw Open. 2020;3(5):e204442