title: Epidemiology of sports-related concussion in seven US high school and collegiate sports.
abstract: BACKGROUND
  The epidemiology of sports-related concussion is not well-described in the literature. This paper presents a descriptive epidemiology of concussion in seven high school and collegiate sports.
  
  
  METHODS
  We used the data from Concussion Prevention Initiative (CPI), which enrolled 8905 athletes at 210 high schools and 26 colleges in a prospective cohort study of 7 sports (football, men's and women's soccer, men's and women's lacrosse, and men's and women's ice hockey) between 1999 and 2001. Injury risks and injury rates were used to characterize the incidence of concussion, and changes in symptoms over time were described.
  
  
  RESULTS
  A total of 375 concussions were observed. The incidence of concussion was highest in football, followed by women's lacrosse, men's lacrosse, men's soccer, and women's soccer (only 10 ice hockey teams were included, too few to quantify incidence). The rate of incident concussion was strongly associated with history of concussion in the previous 24 months (rate ratio = 5.5; 95 %CI: 3.9, 7.8, for 2 or more concussions relative to no previous concussion). The most common symptoms at time of injury were headache (87 %), balance problems/dizziness (77 %), and feeling "in a fog" (62 %). Loss of consciousness and amnesia were present in relatively few cases (9 and 30 %). The most common mechanism of injury was collision with another player.
  
  
  CONCLUSIONS
  Sports-related concussions present with a diverse range of symptoms and are associated with previous concussion history.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. smarshall@unc.edu.|Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. smarshall@unc.edu.|Matthew Gfeller Sport-Related Traumatic Brain Injury Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. smarshall@unc.edu.|Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. smarshall@unc.edu.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
authors.affiliation: Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.|Matthew Gfeller Sport-Related Traumatic Brain Injury Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.|Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
authors.affiliation: Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Shankar
authors.affiliation: Neuroscience Center, Waukesha Memorial Hospital, Waukesha, WI, USA.|Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: McCrea
authors.affiliation: Neurosurgery Service, Emerson Hospital, Concord, MA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Cantu
keywords: Football; Head injury; Lacrosse; Soccer; Traumatic brain injury