Age gradient in the cost-effectiveness of bicycle helmets.

OBJECTIVES This study analyzed the reduction in risk of head injuries associated with use of bicycle helmets among persons ages 3 to 70 and the cost-effectiveness of helmet use based on this estimated risk reduction. METHODS To derive our cost-effectiveness estimates, we combined injury incidence data gathered through a detailed and comprehensive injury registration system in Norway, acute medical treatment cost information for the Norwegian health service, and information reported in the scientific literature regarding the health protective effects of helmet use. The analysis included all cases of head injuries reported through the registration system from 1990 through 1996. We performed an age-stratified analysis to determine the incidence of bicycle-related head injuries, the 5-year reduction in absolute risk of injury, the number needed to treat, and the cost-effectiveness of helmet use. To test the robustness of the findings to parameter assumptions, we performed sensitivity analysis. RESULTS The risk of head injury was highest among children aged 5 to 16. The greatest reduction in absolute risk of head injury, 1.0 to 1.4% over 5 years estimated helmet lifetime, occurred among children who started using a helmet between the ages of 3 and 13. Estimates indicate that it would cost approximately U.S. $2,200 in bicycle helmet expenses to prevent any one upper head injury in children ages 3-13. In contrast, it would cost U.S. $10,000-25,000 to avoid a single injury among adults. CONCLUSIONS Bicycle safety helmets appear to be several times more cost-effective for children than adults, primarily because of the higher risk of head injury among children. Programs aiming to increase helmet use should consider the differences in injury risk and cost-effectiveness among different age groups and target their efforts accordingly.