In a government-supported study of more than 300 fatal and non-fatal bicycle accidents, Johns Hopkins researchers found that alcohol was a factor in at least a third of the deaths.
"Alcohol may have an even greater impact on cyclists than on motorists," says Guohua Li, M.D., the study's lead author and an assistant professor of emergency medicine at Hopkins. "Riding a bicycle requires more physical coordination and concentration than driving a car, and biking performance declines more rapidly as the rider's blood-alcohol level increases."
Although cycling -- drunken or sober -- accounts for only a small percentage of all traffic-related trauma in the United States, it is the nation's leading cause of recreational injury, resulting each year in about 600,000 emergency department visits, 20,000 hospitalizations, 900 deaths and $1 billion in medical care. Hopkins researchers say cycling safety programs that include warnings against intoxication could reduce the estimated 60,000 alcohol-related cycling injuries, 300 deaths and $250 million treatment pricetag nationwide each year.
"It's been shown consistently that alcohol use increases the likelihood of risky behavior by drivers, and our results suggest this is also true for cyclists," says Li. The results were published in the December issue of Alcoholism: Clinical and Experimental Research.
Researchers compared all 63 fatal cycling accidents in Maryland involving cyclists age 10 and older with 253 non-fatal cycling injuries from 1987 to 1994. Results show the fatally injured cyclists were nearly twice as likely as the seriously injured cyclists to have been drinking (30 percent versus 16 percent) and to be legally intoxicated (22 percent versus 13 percent). Cyclists who died at the accident scene were nearly four times as likely as those who died at hospitals to be legally intoxicated (35 percent versus 9 percent).
Among those seriously injured, intoxication tripled the likelihood of death, probably because fewer drunken cyclists wore safety helmets (6 percent) than the sober cyclists (31 percent). Ninety percent of the fatalities and 30 percent of the non-fatal accidents resulted from bicycle-motor vehicle collisions.
In both fatal and non-fatal cases, intoxication was more common among men ages 20 to 39 and those injured while cycling at night. Among those testing positive for alcohol, 74 percent of the fatalities and 78 percent of the non-fatalities had blood-alcohol concentrations of 0.10 percent or higher.
"Previous research on bicycling injury was conducted predominantly in children and focused on the effectiveness of safety helmets, but our results suggest that preventing intoxicated biking should be incorporated into helmet campaigns and other bicycling safety programs," says Susan Baker, M.P.H, a co-author and professor of health policy and management at Hopkins.
The study's estimates probably are conservative because blood-alcohol tests frequently were not given to cyclists until several hours after the accidents, and because medical examiners do not report that motorists were involved in fatal bicycle accidents, says Li.
More than 100 million bicycles are in use in the United States, primarily for recreation, and more than 45 percent of Americans ride bicycles at least occasionally. Helmets greatly reduce the risk of head injury, which contribute to most bicycle-related deaths, but more than 80 percent of U.S. cyclists do not wear helmets.
The study, which was supported primarily by the National Institute on Alcohol Abuse and Alcoholism and in part by the Centers for Disease Control and Prevention, included the Office of the Chief Medical Examiner of Maryland, the National Study Center for Trauma and Emergency Medical Systems, and the University of Maryland at Baltimore School of Medicine.