DENVER – The prevalence of drinking and driving has steadily declined since the first National Roadside Survey of Alcohol and Drug Use by Drivers was conducted in 1973.
In the most recent of these surveys, just over 12% of weekend nighttime drivers had a detectable blood alcohol level. In contrast, that figure was 36% in the 1973 survey, dropping to 30% in the 1986 survey and 17% in 1996, Maria Vegega, Ph.D., reported at the annual meeting of the American Public Health Association.
For the most recent survey, conducted in 2007, nearly 10,000 noncommercial drivers were randomly stopped and anonymously tested for alcohol and drugs at 300 locations between the hours of 9:30 a.m. on Friday and 3 a.m. on Sunday. Of daytime drivers, 1% had a detectable blood alcohol level; of nighttime drivers, more than 12% had detectable levels.
Additionally, the 2007 survey represents the first time data have been collected on the prevalence of drug use in a random sample of drivers. Overall, 16.3% of drivers had detectable levels of drugs in their blood or oral fluid. Illegal drugs were detected in 11.3% of drivers, with marijuana being most common. The most commonly detected prescription medications were stimulants, found in 3.3% of drivers, followed by narcotic analgesics in 1.6%, sedatives in 0.8%, and antidepressants in 0.7% of all drivers.
A blood alcohol level above the legal limit was present in 4.1% of drivers with a positive drug result, compared with 1.7% of drug-negative drivers.
An ongoing large case-control study is being conducted to identify which drugs are associated with a higher risk of crashes. Results are anticipated in 2012.
In other findings of the 2007 survey, 2.2% of weekend nighttime drivers were intoxicated as defined by a blood alcohol level of 0.08 g/dL or more; the prevalence rose to 4.8% among late-night drivers tested from 1 a.m. to 3 a.m. In the 1973 survey, 7.5% of all nighttime drivers had a blood alcohol level in this range, a rate that declined to 5.4% in 1986 and 4.3% in 1996, according to Dr. Vegega, chief of the behavioral research division at the National Highway Traffic Safety Administration, which conducts the National Roadside Survey.
In the 2007 survey, the proportion of nighttime drivers with a blood alcohol level of at least 0.08 g/dL varied by age from a high of 3.6% among drivers aged 65 and over to 0.9% in those under age 21. Nighttime motorcycle drivers had a 5.6% prevalence of a blood alcohol level of 0.08 g/dL or more, compared to a 1.3% rate for drivers of sports utility vehicles, 3.3% for those at the helm of pickup trucks, and 2.3% for passenger car drivers.
Dr. Vegega declared having no relevant financial disclosures.