Incidence of and Mortality From Amyotrophic Lateral Sclerosis in National Football League Athletes.
Level 3 - non-randomized controlled study
Retrospective population-based cohort study with nested case-control analysis
PubMed 34910152 · doi:10.1001/jamanetworkopen.2021.38801
What was done
A retrospective population-based cohort study analyzed 19,423 male NFL athletes who debuted between 1960 and 2019 and played in at least one professional game, followed for 493,168 cumulative person-years (mean 30.6 years). ALS diagnoses and mortality were identified using public records, news reports, obituaries, sports aggregators, and the National Death Index. Standardized incidence ratios (SIR) and standardized mortality ratios (SMR) were calculated using US population surveillance data adjusted for age, sex, and race. A nested case-control design matched athletes with and without ALS by debut year to assess career duration, body mass index, position, race, birth location, and markers of fame.
What was found
Thirty-eight players were diagnosed with ALS and 28 died during the study window. Compared with the US male population, NFL athletes had significantly elevated ALS incidence (SIR, 3.59; 95% CI, 2.58–4.93) and ALS mortality (SMR, 3.94; 95% CI, 2.62–5.69). Nested case-control analysis showed players diagnosed with ALS had significantly longer NFL careers (mean 7.0 vs. 4.5 years; OR, 1.2; 95% CI, 1.1–1.3). No differences were found for body mass index, position played, race, birth location, or fame proxies.
Why it matters
This study provides evidence linking professional American football participation to a nearly fourfold elevation in ALS risk, identifying career duration as a potential dose-dependent factor.
Limits
Case ascertainment relied partly on obituaries and public media reports, potentially introducing underreporting or misclassification. Direct measures of head impacts, concussions, genetic risk factors, and non-football occupational exposures were unavailable. The findings are restricted to elite male professional athletes and may not generalize to lower levels of play or females.
Cited by
- supports The average NFL player's career lasts approximately three years.