Drivers who Test Positive for Drug Use More Likely to be in Fatal Car Crash

A recent study shows that drivers who test positive for drugs have triple the risk of getting into a fatal car crash.

According to researchers from Columbia University's Mailman School of Public Health, they found that drug use is significantly associated with a significantly increased risk of fatal crash involvement, particularly when used in combination with alcohol.

The study provides essential data for understanding the joint effect of both alcohol and drugs on driving safety.

The study looked at extensive data from the National Highway Traffic Safety Administration: the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers and the Fatality Analysis Reporting System (FARS), a repository of investigation data for all crashes that resulted in at least one fatality within 30 days of the crash and that occurred on a public road.

The second source of data also contains thorough information regarding the crash circumstances and he individuals and vehicles involved in the accidents. This is the first study to examine both types of issues together.

Study results of the Mailman school study, led by Guohua Li, MD., professor of Epidemiolgy and the director of the Center for Injury Epidemiology and Prevention showed that 31.9 percent of the drivers involved in fatal car crashes and 13.7 percent of the drivers interviewed at the roadside survey tested positive for at least one non-alcohol drug. Background information from the study shows that drivers who tested positive for drugs were actually three times more likely to be involved in a car crash. Among the drugs found in a percentage of drivers, depressants showed the highest risks followed by stimulants, marijuana and narcotics.

Results also showed that 57 percent of cases and 8.8 percent of the controls had elevated alcohol blood levels, increasing the risk of being involved in a car crash. Close to one-fifth of the cases tested positive for alcohol and one or more drugs, compared with 2.2 percent of the controls.

However, the study concludes that these findings could be carefully interpreted as just because a driver tests positive for drug use, it doesn't mean he or she was affected by it during the time of the crash.

"The possible interaction of drugs in combination with alcohol on driving safety has long been a concern," said Dr. Li, who is also professor of Anesthesiology at Columbia, via a press release. "While alcohol-impaired driving remains the greatest threat to traffic safety, these findings about drugged driving are particularly salient in light of the increases in the availability of prescription stimulants and opioids over the past decade."

More information regarding the study can be found via the journal Accident Analysis and Prevention.