The effects of bicycle helmet legislation on cycling-related injury: The ratio of head to arm injuries over time

Legislation for the mandatory use of bicycle helmets is a controversial issue. The analysis presented in this paper examines the ratio of cycling-related head to arm injuries using hospital admissions data in New South Wales. The analysis is based on the idea that even if the numbers of cyclists has dropped over time, the relative injury rates (head versus arm) should remain unchanged unless some factor is differentially impacting on one type of injury, for example, helmet use reducing head injuries but not affecting arm injuries. Results indicate that there was already a fall in the ratio of head to arm injuries before the mandatory helmet legislation was introduced in 1991. After the introduction of bicycle helmet legislation, there was a continued but declining reduction in the ratio of head injuries relative to arm injuries for most age groups. It is likely that factors other than the mandatory helmet legislation reduced head injuries among cyclists.