To the Editor.
—The article by Dr Kraus and colleagues1 concerning effects of a mandatory motorcycle helmet law in California is an excellent example of how medical bias can produce studies designed chiefly to support a preconceived conclusion. In analyzing the precipitous drop in motorcycle crash fatalities following implementation of a helmet law, the authors completely fail to take into consideration the major determinant of that decline—the unprecedented reduction in the number of accidents involving motorcyclists. Both common sense and statistics inform us that if fewer crashes are occurring, then fewer motorcyclists will be killed or injured.During the 4 years preceding the helmet law, motorcycle crashes declined at an average rate of 9% annually, and motorcycle-related deaths showed nearly an identical decrease of 8.6% per year. However, motorcycle crashes in California decreased from 18203 in 1991 to 13568 in 1992.2 This 26% decrease is nearly three times
Nunley DL. Motorcycle Helmet Use and Injuries. JAMA. 1995;274(12):941. doi:10.1001/jama.1995.03530120033025