title: Reliability of concussion history in former professional football players.
abstract: OBJECTIVE
  The reliability of athletes to recall and self-report a concussion history has never been quantified. This study examined the reliability of the self-report concussion history measure and explored determinants of recall in the number of self-reported concussions in a group of retired professional football players.
  
  
  METHODS
  In 2001, a short questionnaire was administered to a cohort of former professional football players to ascertain the number of self-reported concussions they sustained during their professional playing careers. In 2010, the same instrument was readministered to a subset (n = 899) of the original cohort to assess reliability.
  
  
  RESULTS
  Overall reliability was moderate (weighted Cohen κ = 0.48). The majority (62.1%) reported the same number of concussions in both administrations (2001 and 2010); 31.4% reported more concussions in the second administration. Compared with the "same number reported" group, the "greater number reported" group had more deficits in the second administration in their Short Form 36 physical health (composite score combining physical functioning, role physical, bodily pain, general health) and mental health (e.g., composite score combining vitality, social functioning, role emotional) scales.
  
  
  CONCLUSIONS
  The self-reported concussion history had moderate reliability in former professional football players, on the basis of two administrations of the same instrument, 9 yr apart. However, changes in health status may be differentially associated with recall of concussions.
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7435, USA.
authors.forename: Zachary Y
authors.initials: ZY
authors.lastname: Kerr
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
mesh_terms: D000368:Aged; D001924:Brain Concussion / Q000523:psychology*; D005538:Football / Q000293:injuries*; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires