Bike Riding And Alcohol: A Lethal Combination

Ever since Mothers Against Drunk Driving (MADD) was founded in California in 1980, it has been a potent force against driving automobiles while intoxicated. There is now another challenge that MADD may want to address: drunken bikers. Researchers have linked one out of three fatal or serious bike accidents involving persons aged 15 years or older to alcohol consumption.

Bicycling as a form of recreation and exercise, and to some extent as a means of transportation, has become increasingly popular in the United States in recent years. It has been shown that riding a bike requires a higher level of psychomotor skills than driving a car and that biking performance in controlled lab conditions declines progressively as blood concentrations of alcohol increase.

However, the role of alcohol consumption in biking injuries has not been adequately addressed in rigorously designed epidemiological studies. So Guohua Li, M.D., Ph.D., of the department of emergency medicine at Johns Hopkins University School of Medicine in Baltimore and his coworkers decided to conduct such an investigation.

The researchers zeroed in on 34 persons 15 years or older who had died by bike injury and whose deaths had been evaluated by the medical examiner’s office. They then matched these 34 cases with 106 controls. The controls were persons who were biking in the same areas where the study subjects had died and also in the same month of the year, on the same day of the year, and at the same time of day as the study cases, and when stopped, agreed to an interview and alcohol breath test for the study.

The investigators also focused on 90 persons 15 years or older who had been injured while biking and who had been treated for their injuries at the shock trauma center. These 90 cases were matched with 236 controls. Once again, controls were biking in the same areas and during the same month, on the same day of the year, and at the same time of day as the cases had been. These individuals also agreed to an interview and an alcohol breath test.

Thus, altogether there were 124 cases of people who had been killed or injured while biking and 342 controls.

The scientists then looked at data for these 124 cases and 342 controls to determine who had been biking while under the influence of alcohol. They then compared the alcohol levels for the two groups. They found that only 3 percent of controls had been biking while under the influence of blood alcohol concentrations of 0.02 grams per deciliter or higher, which is comparable to one alcoholic drink. (A blood alcohol concentration of 0.08 grams per deciliter is the legal level of drunkenness in most states, and that is comparable to four or five alcoholic drinks.) In contrast, some 9 percent of bikers who had been seriously injured while biking had been biking under the influence of alcohol at 0.02 grams per deciliter or higher, and some 24 percent of bikers who had died while biking had been biking under the influence of alcohol at 0.02 grams per deciliter or higher.

“Alcohol use while bicycle riding is associated with a substantially increased risk of fatal or serious injury,” Li and his team conclude in the February 21 Journal of the American Medical Association.

Thus, if drinking while biking truly opens people to injury or even death, one might ask: Does wearing a biking helmet protect a bicyclist from injury or death while under the influence of alcohol? The answer is, Maybe. But the study also revealed that bicyclists under the influence tend to not wear helmets. Overall, bikers with an alcohol level of less than 0.02 grams per deciliter were seven times as likely to be wearing a helmet as were those with a higher alcohol level.

The study, “Use of Alcohol as a Risk Factor for Bicycling Injury,” is posted on the Web at http://jama.ama-assn.org/issues/v285n7/rfull/joc01523.html. ▪