Alcohol policies and impaired driving in the United States: Effects of driving- vs. drinking-oriented policies.

AIMS To test the hypotheses that stronger policy environments are associated with less impaired driving and that driving-oriented and drinking-oriented policy subgroups are independently associated with impaired driving. DESIGN State-level data on 29 policies in 50 states from 2001-2009 were used as lagged exposures in generalized linear regression models to predict self-reported impaired driving. SETTING Fifty United States and Washington, D.C. PARTICIPANTS A total of 1,292,245 adults (≥ 18 years old) biennially from 2002-2010. MEASURES Alcohol Policy Scale scores representing the alcohol policy environment were created by summing policies weighted by their efficacy and degree of implementation by state-year. Past-30-day alcohol-impaired driving from 2002-2010 was obtained from the Behavioral Risk Factor Surveillance System surveys. FINDINGS Higher Alcohol Policy Scale scores are strongly associated with lower state-level prevalence and individual-level risk of impaired driving. After accounting for driving-oriented policies, drinking-oriented policies had a robust independent association with reduced likelihood of impaired driving. Reduced binge drinking mediates the relationship between drinking-oriented policies and impaired driving, and driving-oriented policies reduce the likelihood of impaired driving among binge drinkers. CONCLUSIONS Efforts to reduce alcohol-impaired driving should focus on reducing excessive drinking in addition to preventing driving among those who are impaired.