title: The epidemiology of new versus recurrent sports concussions among high school athletes, 2005-2010.
abstract: OBJECTIVE
  To compare new versus recurrent concussions with respect to constellation of symptoms, symptom severity, symptom resolution; evaluate potential subset differences with respect to gender and sport; and to compare mechanisms and activities associated with new versus recurrent concussions.
  
  
  METHODS
  Sports-related injury and exposure data were collected for nine sports from 2005 to 2010 from 100 nationally representative US high schools.
  
  
  RESULTS
  Nationally, an estimated 732,805 concussions occurred. Of these reported concussions, 13.2% were recurrent. The rate of new concussions was 22.2 per 100,000 athletic exposures while the rate of recurrent concussions was 3.1 per 100,000 athletic exposures (RR 7.23, 95% CI 6.39 to 8.17, p<0.001). While 0.6% of new concussion symptoms took >1 month to resolve, 6.5% of recurrent concussion symptoms took >1 month to resolve (IPR 10.35; 95% CI 4.62 to 23.16; p<0.001). Loss of consciousness was reported more often with recurrent (7.7%) than new concussions (4.4%) (IPR 1.76; 95% CI 1.02 to 3.03; p=0.043). A greater proportion of athletes sustaining recurrent concussions returned to play in >3 weeks (7.5%) or were medically disqualified (16.2%) than athletes sustaining new concussions (3.8%; IPR 1.95; 95% CI 1.01 to 3.77; p=0.047 and 2.9%; IPR 5.58; 95% CI 3.50 to 8.88; p<0.001, respectively). The majority of new and recurrent concussions resulted from contact with another person (73.4% and 77.9%, respectively).
  
  
  CONCLUSIONS
  Athletes sustaining recurrent concussions had longer symptom resolution times, were kept out of play longer and reported loss of consciousness more frequently than athletes sustaining new concussions. With the possibility of long-term impairment and other negative sequelae, proper management and prevention of concussions at the high school level is imperative.
authors.affiliation: The Research Institute at Nationwide Children's Hospital, Center for Injury Research and Policy, Columbus, Ohio 43205, USA
authors.forename: Lianne
authors.initials: L
authors.lastname: Castile
authors.forename: Christy L
authors.initials: CL
authors.lastname: Collins
authors.forename: Natalie M
authors.initials: NM
authors.lastname: McIlvain
authors.forename: R Dawn
authors.initials: RD
authors.lastname: Comstock
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000453:epidemiology*; D001924:Brain Concussion / Q000150:complications / Q000453:epidemiology* / Q000534:rehabilitation; D005260:Female; D006801:Humans; D007902:Length of Stay; D008297:Male; D020127:Recovery of Function; D012008:Recurrence; D014481:United States / Q000453:epidemiology