Match incidence rates (injuries/1000 h) in players with a diagnosed concussion and those that did not have a diagnosed concussion, IRRs used to determine effect size
| Player group | All injuries | Exposure (hours) | Incidence (95% CI) | IRR (95% CI) |
|---|---|---|---|---|
| Players without diagnosed concussion (n=660) | 1398 | 18 500 | 75.6 (71.7 to 79.7) | Ref |
| Players with diagnosed concussion (n=135) | ||||
| Postinjury (following return to play) | 119 | 976 | 122.1 (105.8 to 141.0) | 1.6* (1.4 to 1.9) |
| Pre-injury (before the concussion) | 67 | 799 | 83.9 (66.0 to 106.6) | 1.1 (0.8 to 1.5) |
*Shows significant difference versus the reference group.
IRR, Incidence rate ratio; Ref, denotes reference group for IRR calculations.