The role of alcohol in nonfatal bicycle injuries

To assess the risk of nonfatal bicycle injury related to blood alcohol concentration (BAC) an unmatched case-control study was conducted in Helsinki in 1986. Eligible cases were the 140 adults injured either in motor vehicle or other bicycle accidents occurring between 3 p.m. and 10 p.m., who arrived at hospital within six hours of injury. Seven hundred bicyclists from the street were randomly selected as controls. BAC was measured with a breathalyzer. A major difference in alcohol involvement was found between cases (24.1%) and controls (4.0%). The injury risk estimate (odds ratio) of an inebriated bicyclist was at least ten-fold at BACs above 100 mg/dl compared to a sober bicyclist. Alcohol increased the bicyclist's risk of injury from falling more than from collision. As an unprotected road user, an inebriated bicyclist greatly increases his own risk of injury but seldom causes danger to other road users.