Trends in head injuries associated with mandatory bicycle helmet legislation targeting children and adolescents.

BACKGROUND

Bicycling related head injuries (HIs) can be severe. Helmet use reduces head injury risk; however, there are few controlled studies of the effect of helmet legislation. We conducted this study to investigate changes in HIs after bicycle helmet legislation targeting those <18 in Alberta, Canada in 2002.

METHODS

Bicyclist and pedestrian (control) HI rates and HIs as a proportion of all injuries were compared for the three years (1999-2001) before and four years (2003-2006) after bicycle helmet legislation in three age groups (children: <13, adolescents: 13-17, and adults: 18+).

RESULTS

There were 41,270 ED visits and 2782 hospitalizations for bicyclists and 9836 ED visits and 2029 hospitalizations for pedestrians (excluding the legislation year 2002). The rate of ED HIs declined for child bicyclists and child pedestrians, while the rate of non-HIs declined in adult bicyclists and child pedestrians. The rate of hospitalized HIs declined in child bicyclists and all ages of pedestrians while non-HI rates declined for child and adult pedestrians. Non-HI rates for adolescent and adult bicyclists increased. After adjusting for sex and location, the proportion of ED bicycle HIs declined by 9% (APR=0.91; 95% CI: 0.86, 0.95) in children, was unchanged among adolescents and increased in adults (APR=1.08; 95% CI: 1.01, 1.15). The proportion of bicycle HI related hospitalizations decreased by 30% (APR=0.70; 95% CI: 0.55, 0.90) in children, 36% (APR=0.64; 95% CI: 0.49, 0.84) in adolescents and 24% (APR=0.76; 95% CI: 0.63, 0.91) in adults. There were no observed changes in the proportion of pedestrian HIs resulting in ED visits or hospitalizations.

INTERPRETATION

Our data indicate significant declines in the proportion of child bicyclist ED HIs and child, adolescent and adult bicyclist HI hospitalizations. This is in contrast to no significant trends in the proportion of ED or hospitalized HIs among pedestrians and the unexpected increases in the proportion of ED HIs for adult bicyclists. Comparing bicyclist and pedestrian trends in the proportion of child and adolescent HIs suggests a bicycle helmet legislation effect.