Cyclist head and facial injury risk in relation to helmet fit: a case-control study.

INTRODUCTION We examined the effect of bicycle helmet fit and position on head and facial injuries. METHODS Cases were helmeted cyclists with a head (n=297) or facial (n=289) injury. Controls were helmeted cyclists with other injuries, excluding the neck. Participants were interviewed in seven Alberta emergency departments or by telephone; injury data were collected from charts. Missing values were imputed using chained equations and custom prediction imputation models. RESULTS Compared with excellent helmet fit, those with poor fit had increased odds of head injury (odds ratio [OR] = 3.38, 95% confidence interval [CI]: 1.06-10.74). Compared with a helmet that stayed centred, those whose helmet tilted back (OR = 2.90, 95% CI: 1.54-5.47), shifted (OR = 1.91, 95% CI: 1.01-3.63) or came off (OR = 6.72, 95% CI: 2.86-15.82) had higher odds of head injury. A helmet that tilted back (OR = 4.81, 95% CI: 2.74-8.46), shifted (OR = 1.83, 95% CI: 1.04-3.19) or came off (OR = 3.31, 95% CI: 1.24-8.85) also increased the odds of facial injury. CONCLUSION Our findings have implications for consumer and retail education programs.