Table 1

Variables collected by reviewers for analysis for each head collision event (HCE) identified

No. players involvedThe number of players involved in the HCE, including the injured player (numerical)
Medical assessmentWhether the injured player received assessment from team medical personnel (binary)
Assessment locationThe location where injured players were assessed by medical personnel, includes: no assessment, on field, on sidelines, elsewhere in the stadium/hospital
Time assessedTime that injured player was assessed by medical personnel until return to play in seconds (s)
Return to playTime until injured player returned to play, includes: immediately following assessment on pitch, immediately following assessment on sidelines, in the same half, removed from game, removed from game via APCS
ScoreScore of the game in reference to the injured player’s team, includes; tied, winning, losing
FoulWhether the referee determined there was a foul for the HCE (binary)
No. signs of concussionThe number of signs of concussion demonstrated by the injured player, includes: slow to get up, clutching of the head, disorientation/daze, loss of consciousness, obvious disequilibrium
  • APCS, additional permanent concussion substitute.