Identifying the Population Sources of Alcohol Impaired Driving: An Assessment of Context Specific Drinking Risks

High-risk drinkers who drink in high-risk contexts like bars are recognized as a primary source of alcohol-impaired drivers and motor vehicle crashes within communities. We assess the contributions of drinking in other contexts to these outcomes. Self-report survey data from 8,553 adults in 50 California cities were used to estimate rates of driving after drinking (DAD; driving within 4 hours of drinking any alcohol) and a measure of alcohol-impaired driving (AID; driving when having had "too much" to safely drive home) associated with drinking in bars, homes, restaurants, parties, and other contexts. Frequent drinking (b = .0588, z = 2.17, p = .030) and drinking outside the home, χ (4) = 74.46, p < .001, at bars (b = .1418, z = 1.97, p = .049), and at restaurants (b = .2694, z = 5.60, p < .001) were related to greater DAD; lower risks were associated with drinking at home (b = -.0607, z = -2.16, p = .031). AID frequency was directly proportional to DAD (b = .0863, z = 8.43, p < .001) with no differences observed across contexts. Within a community of 100,000 persons over 6 months, 879 AID events were attributed to drinking at 102 restaurants and 726 AID events to drinking at 15 bars. Drinking at bars and restaurants contributes about equally to DAD and AID, with AID events concentrated in small populations that frequent relatively few bars and broadly distributed across large populations that frequent many restaurants. High frequencies of drinking at home were also associated with surprisingly large numbers of DAD and AID events. Observed differences between individual and community risks for DAD and AID must be addressed in place-based community prevention programs.