Objective: To determine the effects of the California motorcycle helmet use law on statewide fatalities and a large sample of nonfatal injuries before and after law implementation.
Design: Police reports and death certificates were collected for motorcycle crash fatalities in California for 1991 (prelaw) and 1992 (postlaw). Official counts of registered motorcycles provided a statewide basis for exposure to a motorcycle crash. Autopsy results were collected for fatalities in 11 counties. Hospital records were reviewed for nonfatal injuries in 28 hospitals in 10 of the 11 counties. Police reports were linked to injury data for the riders.
Subjects and patients: A total of 850 fatalities and injury data for 547 fatally injured riders and 3252 nonfatally injured patients.
Main outcome measures: Changes in number and rates among statewide fatalities were estimated. The number and pattern of head injuries in fatally and nonfatally injured motorcycle riders were evaluated.
Results: After implementation of the helmet use law, statewide motorcycle crash fatalities decreased by 37.5%, from 523 fatalities in 1991 to 327 in 1992, more than 37%, and an estimated 92 to 122 fatalities were prevented. Motorcycle fatality rates were reduced by 26.5%, from 70.1 per 100,000 registered motorcycles in 1991 to 51.5 per 100,000 in 1992. Head injuries decreased significantly among both fatally and nonfatally injured motorcyclists.
Conclusion: Enactment of an unrestricted helmet law significantly reduces the incidence of motorcycle crash fatalities and the number and severity of head injuries.