Age-related trends in drug-involved driving in the United States, 2005–2009

Compared with alcohol-involved driving, relatively little is known about the rates and trends in drug-involved driving in the United States. Of the 12,087 fatally injured drivers with known drug testing results in 2009, 33 percent tested positive for drugs, which suggests that drug-involved driving is a public health concern on par with drunk driving. A confluence of factors interact to affect drug-involved driving rates, of which age is particularly significant. Methods: In order to assess the impact of age and other relevant factors on drug-involved driving, the Fatality Analysis Reporting System (FARS), maintained by the National Highway Traffic Safety Administration (NHTSA), was analyzed. FARS includes demographic and drug-testing data for up to three drugs from fatally injured crash victims in all fifty states. Logistic regression analysis was conducted comparing drug positive drivers to all other drivers for 2005-2009. Predictors included age, sex, race/ethnicity, alcohol use, and other risk factors. Results: Younger fatally-injured drivers (<=age 15-24) are twice as likely to test positive for drugs than their oldest counterparts (over age 65) (p<.0001). The type of drug reported also varies by age. Younger fatally injured drivers who were tested were positive for cannabinoids 43 percent of the time. On average, this rate decreased by 8 percentage points in each subsequent decade of life. Middle aged drivers were more likely to test positive for stimulants. Conclusions: Drug-involved driving is a serious public health concern. Intervention efforts need to be sensitive to age-related differences in drug use.