National rugby league match scheduling and rate of concussion

Objective: The aims of this study were to evaluate the relationship between pre-match rest days, match location, time of season, and match outcome with diagnosed concussion and use of the Concussion Interchange Rule (CIR) during the 2014 NRL season. Design: Descriptive observational study. Method: This study reviewed all instances of diagnosed concussions, CIR activations, and match characteristics during the 2014 NRL season. Information pertaining to the use of the CIR was obtained from the league. Each club provided information of diagnosed concussion. Results: A total of 402 NRL games were analyzed, the concussion interchange rule was activated 167 times, and 60 concussions were diagnosed in 53 of the matches. A significantly greater proportion of concussions occurred during the first match of the season (38% vs. 15% of in-season matches; p = 0.02). Days of rest, match location, season stage, and match outcome were not associated with a higher proportion of concussions. Furthermore, we did not detect a significant association between CIR activation and days of rest prior to the match, opponent rest prior to the match, match location, round of the season, or match outcome. Conclusions: A significantly greater proportion of concussions were diagnosed during the first match of the season. Days between matches, opponent days of rest, match location, or other rounds (aside from round 1) of the season were not associated with CIR activation or diagnosed concussion. Varied game scheduling during the season does not appear to be associated with increased risk for concussion or use of the CIR in the NRL.