Some epidemiologic features of motorcycle collision injuries. I. Introduction, methods and factors associated with incidence.

Using official police reports and hospital admission and emergency room medical records, 1273 persons with confirmed medically treated motorcycle injury were identified in Sacramento County, California, during 1970. Less than 39% of all injured motorcyclists were identified in this study using only official police reports. The annual incidence rate was highest for 18-year-old male drivers. In addition to age of driver, risk of injury was associated with drivers of short stature (less than 173 cm) operating an intermediate or larger size motorcycle. Risk of injury was higher for drivers with training than for those without training or those who operated their motorcycles frequently regardless of type of use. Risk of injury was not related to make of motorcycle but was related to engine size. Two-thirds of the injury-producing collisions involved a motorcycle and a second motor vehicle. Motorcycle collisions occurred most fre quently during the afternoon and early evening hours and during the summer months, but peaks in incidence of collisions occurred during weeks which included a holiday.