Outlets, drinking and driving: a multilevel analysis of availability.

OBJECTIVE This study examines the degree to which the physical availability of alcohol as measured by outlet densities is related to self-reported individual drinking patterns, preferred drinking location, as well as both driving after drinking (DAD) and driving while intoxicated (DWI). METHOD Data from 7,826 drinkers were obtained from a general-population telephone survey of 1,353 zip code areas in California. Measures of individual alcohol consumption included drinking frequency, drinks per occasion and variance in quantities consumed per occasion. Preferred drinking locations included bars, restaurants and the homes of drinkers and of their friends. DAD was defined as driving a motor vehicle within 4 hours of having one or more alcoholic drinks, and DWI was defined as driving after having too much to drink and drive safely. Geographic measures of outlet densities were obtained for bars, restaurants and off-premises establishments, using zip codes as geographic units of analysis. Hierarchical linear modeling was used to relate outlet densities within and surrounding respondents' area of residence to respondents' drinking and to respondents' drinking and driving. RESULTS Whereas restaurant densities were directly related to greater drinking frequencies and DAD, bar densities were inversely related to DAD. There were no direct effects of drinking patterns on drinking and driving. Drinking and driving was strongly related to drinking location preference (e.g., bars and restaurants) only when considered simultaneously with individual drinking patterns, particularly drinking frequency. CONCLUSIONS Increased restaurant density is strongly related to higher rates of both self-reported driving after drinking and drinking frequency. The strongest influence on both driving after drinking and driving while intoxicated is preferred drinking location considered together with individual drinking patterns. Outlet density and preferred drinking location when considered together with individual drinking patterns support driving after drinking and thereby increase the potential for alcohol-related accidents.