Table 4

Results of multiple multilevel poisson regression models for game-related injury and concussion in Midget (15–17 years) ice hockey players in Calgary, Edmonton and Vancouver (2015–2016, 2016–2017, 2017–2018) in the lower 70% by division of play (with MICE Imputation)

CovariateIncidence rate ratio (95% CI)
All injuryaConcussionb
Body checking cohort
 Body checking1 (reference)1 (reference)
 No body checking0.38 (0.24 to 0.6)0.49 (0.26 to 0.89)
Year of play
 First1 (reference)1 (reference)
 Second0.91 (0.64 to 1.3)0.65 (0.33 to 1.25)
 Third0.83 (0.62 to 1.1)0.65 (0.41 to 1.01)
Player weight
Previous injuryc
 No1 (reference)NA
 Yes1.81 (1.31 to 2.5)
Previous concussiond
 NoNA1 (reference)
 Yes2.5 (1.54 to 4.04)
Position
 Forward1 (reference)1 (reference)
 Defence1.2 (0.87 to 1.65)1.35 (0.83 to 2.19)
 Goalie0.65 (0.35 to 1.19)0.91 (0.38 to 2.17)
  • *Incidence rate ratios and corresponding 95% CI based on Poisson regression analysis offset for exposure game hours, accounting for two levels of clustering: one at subject level and other at team level, and adjusted for covariates (body checking cohort, year of play, player weight, 1-year history injury and position).

  • †Incidence rate ratios and corresponding 95% CI based on Poisson regression analysis offset for exposure game hours, accounting for clustering by team, and covariates (body checking group, year of play, player weight, previous concussion and position).

  • ‡The covariate ‘previous injury in the last year’ includes any injury that occurred in the last 1 year.

  • §The covariate ‘previous concussion’ includes any concussion (lifetime).

  • .MICE, multiple imputation by chained equations; NA, not applicable.;