title: A novel approach to classifying postconcussion symptoms: The application of a new framework to the Post-Concussion Symptom Scale.
abstract: BACKGROUND
  Self-report measures such as the Post-Concussion Symptom Scale (PCSS) are frequently used during baseline and postconcussion testing to evaluate athletes' symptom profiles. However, the common approach of evaluating the total symptom score and/or symptom clusters may not allow for a complete understanding of the nature of athletes' symptom reporting patterns. The primary objective of this study was to apply three "global indices of distress" variables, derived from the Symptom Checklist-90-Revised (SCL-90-R) framework, to the PCSS at baseline and postconcussion. We aimed to evaluate the utility of these symptom indices in relation to four PCSS symptom clusters and the total PCSS symptom score.
  
  
  METHODS
  Participants included college athletes evaluated at baseline (N = 846) and postconcussion (N = 86). Athletes underwent neuropsychological testing at both time points, including completion of the PCSS and a paper/pencil and computerized test battery. Eight symptom indices were derived from the PCSS, and a postconcussion neurocognitive composite score was calculated.
  
  
  RESULTS
  Results showed that there were significant mean increases from baseline to postconcussion on four of the eight symptom indices evaluated. Furthermore, a significant proportion of athletes showed no change from baseline to postconcussion when evaluating the total symptom score, but showed at least a one standard deviation increase in symptom reporting from baseline to postconcussion when evaluating at least one other symptom index (i.e., a global index of distress or symptom cluster). Finally, the three global indices of distress variables, two of the four symptom clusters, and the total symptom score significantly predicted a postconcussion neurocognitive composite score, such that greater postconcussion symptoms were associated with lower postconcussion neurocognitive performance.
  
  
  CONCLUSIONS
  These findings suggest that, in addition to evaluating the postconcussion total symptom score, there may be value in examining more specific symptom indices such as the global indices of distress variables and symptom clusters.
authors.affiliation: a Department of Psychology , Pennsylvania State University , University Park , PA , USA.
authors.forename: Victoria C
authors.initials: VC
authors.lastname: Merritt
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Meyer
authors.forename: Peter A
authors.initials: PA
authors.lastname: Arnett
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000145:classification / Q000175:diagnosis*; D001924:Brain Concussion / Q000145:classification / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D038223:Post-Concussion Syndrome / Q000145:classification / Q000175:diagnosis*; D057566:Self Report; D012720:Severity of Illness Index; D063189:Symptom Assessment; D055815:Young Adult
keywords: Collegiate athletes; Postconcussion symptoms; Sports-related concussion