The cost-effectiveness of compulsory bicycle helmets in New Zealand.

This paper examines the cost-effectiveness for primary school children (age 5-12 years), secondary school children (13-18 years) and adults (over 18 years) of the legislation enacted on 1 January 1994 requiring road-cyclists in New Zealand to wear helmets. The cost to cyclists not in possession of a helmet before they became compulsory of either obtaining one or quitting cycling was compared with the number of deaths and hospitalisations expected to be prevented over the average life of a helmet. Corresponding to Victorian and United States estimates of the efficacy of cycle helmets at preventing serious head injuries, the cost per life saved was $88 379 to $113 744 for primary school children, $694 013 to $817 874 for secondary school children, and $890 041 to $1 014 850 for adults (New Zealand dollars = approximately 0.95 Australian dollars). The cost per hospitalisation avoided was $3304 to $4252, $17 207 to $20 278, and $49 143 to $56 035 respectively. These estimates are extremely sensitive to the estimated efficacy of helmets at protecting cyclists. Mainly anecdotal evidence for New Zealand suggests that they are not to be very effective at preventing serious head injuries; future research into the change in injury patterns as a result of the helmet regulation would be valuable. Nonetheless, the ranking of the abovementioned estimates does not contradict the policy in some parts of the world requiring helmets for children and/or teenagers, but not adults.