Table 3

Game-related outcome variables for Midget (15–17 years) ice hockey injuries in Calgary, Edmonton and Vancouver (2015–2016, 2016–2017 and 2017–2018)

OutcomeInjuryMore severe injury (time loss >7 days)ConcussionMore severe concussion (time loss >10 days)
BC permittedBC prohibitedBC
permitted
No BC
prohibited
BC
permitted
BC
prohibited
BC
permitted
BC
prohibited
No of player-seasons674453674453674453674453
No of injuries or concussions2134013156918411
Player participation (hours)16 440.247793.5116 440.247793.5116 440.247793.5116 440.247793.51
Injury rate, injuries/1000 player-hours (95% CI)*12.96
(9.21, 16.7)
5.13
(1.71, 8.56)
7.97
(4.95, 10.99)
0.64
(0, 1.89)
4.2
(2.63, 5.76)
2.31
(0.62, 4)
2.49
(1.23, 3.75)
0.13
(0, 0.54)
Incidence rate ratio (IRR), (95% CI)†1 (reference)0.35
(0.22, 0.55)
1 (reference)0.08 (0.03, 0.2)1 (reference)0.49
(0.27, 0.91)
1 (reference)0.05
(0.01, 0.36)
Absolute rate reduction (ARR) if BC were not permitted, injuries/1000 player-hours (95% CI)*7.82 (2.74, 12.9)7.33 (4.06, 10.59)1.89 (-0.41, 4.19)2.37 (1.04, 3.69)
No of injuries prevented in one season in Alberta‡886 (311, 1461)830 (460, 1199)214 (-47, 474)268§ (118, 418)
No of injuries prevented in one season in Canada¶7326 (2570, 12083)6861 (3802, 9920)1767 (-387, 3922)2215§ (972, 3459)
  • *Crude rates and ARRs (95% CI) with a design effect accounting for clustering team and subject level for injury and injury (>10 days time-loss), and only team for concussion and concussion (>7 days time-loss), offset for exposure game-hours.

  • †IRRs (95% CI) based on multilevel Poisson regression analysis offset for exposure game-hours, adjusted for clustering (by team and subject for injury and severe injury, and only by team for concussion and severe concussion).

  • ‡The number of injuries prevented (rounded to the nearest integer) is estimated based on ARR and Alberta population participation of male Midget players. The population of male Midget players from Alberta in the 2018–2019 season is 7523. The sample proportion used in the estimation was identified as the lower 70% of 7523 (n=5266) and the average exposure game hours was estimated as 21.5 per player.

  • §Number of severe concussions saved can be greater than the number of concussions saved, given that severe concussions saved is not a subset of concussions saved. Those that still get injured (ie, not saved) may get less severely injured.

  • ¶The number of injuries saved (rounded to the nearest integer) is calculated based on ARR and Canada population participation of male Midget players. The population of male Midget players from Canada in the 2018–2019 season is 62 224. The sample proportion used in the calculation was identified as the lower 70% of 62 224 (n=43 557) and the average exposure game hours was estimated as 21.5 per player.

  • .ARR, absolute rate reduction; BC, body checking; IRR, incidence rate ratio.