title: Division I College Football Concussion Rates Are Higher at Higher Altitudes.
abstract: METHODS
  Retrospective cohort.
  
  
  BACKGROUND
  Participating in sports at high altitude may have a protective effect on the brain, according to research studies. Research using validated data-collection methods in a previously unexplored cohort may better estimate the association between concussion injury risk and altitude.
  
  
  OBJECTIVE
  To determine the association between concussion rates and altitude during college football games.
  
  
  METHODS
  Athletic trainers from 21 Division I football programs provided exposure and injury data to the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) from the 2009-2010 to 2013-2014 academic years. The elevation of each stadium was determined. Concussion rates per 1000 athlete-exposures (AEs) were compared in 2 ways, based on the sample of stadium elevations: (1) median split (elevation higher than 178 m or lower than 178 m), and (2) quartile split. Rate ratios (RRs), rate differences, and 95% confidence intervals (CIs) were computed.
  
  
  RESULTS
  One hundred sixty-nine concussions were reported over 49 040 AEs (3.45/1000 AEs). Using the median split, the concussion rate above 178 m (RR = 4.18/1000 AEs) was 1.47 times the concussion rate below 178 m (RR = 2.84/1000 AEs; 95% CI: 1.09, 2.00; P = .01). The concussion rate at the highest altitude quartile (higher than 284 m; RR = 5.01/1000 AEs) was 1.67 times greater than the concussion rate at the lowest altitude quartile (lower than 43 m; RR = 3.00/1000 AEs; 95% CI: 1.13, 2.48; P = .01).
  
  
  CONCLUSIONS
  College football game concussion rates appear to increase at higher altitudes. The clinical significance of this relatively small increase is unknown. Future research should explore potential physiologic underpinnings associated with concussion risk at relatively higher and lower altitudes.
  
  
  METHODS
  Prognosis, level 2b.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Lynall
authors.forename: Zachary Y
authors.initials: ZY
authors.lastname: Kerr
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Parr
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Hackney
authors.forename: Jason P
authors.initials: JP
authors.lastname: Mihalik
mesh_terms: D000531:Altitude; D001924:Brain Concussion / Q000453:epidemiology*; D005538:Football / Q000293:injuries*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology
keywords: elevation; mild traumatic brain injury; sports epidemiology; sports injury