Alcohol outlet density and intimate partner violence-related emergency department visits.

BACKGROUND: Previous research has identified risk factors for intimate partner violence (IPV) severity, injury, and emergency department (ED) visits. These risk factors have been shown at both the individual level (heavy drinking and other substance use on the part of 1 or both partners) and the neighborhood level (residence in an area characterized by poverty and social disadvantage). Alcohol outlet density has been linked with assaultive violence in community settings, but has not been analyzed in relation to IPV-related ED visits. This study examined the effects of outlet densities on IPV-related ED visits throughout California between July 2005 and December 2008.

METHODS: Half-yearly counts of ED visits related to IPV (E-code 967.3) were computed for each zip code from patient-level public data sets. Alcohol outlet density measures, calculated separately for bars, off-premise outlets, and restaurants, were derived from California Alcohol Beverage Control records. Census-based neighborhood demographic characteristics previously shown to be related to health disparities and IPV (percent black, percent Hispanic, percentage below 150% of poverty line, percent unemployed) were included in models. This study used Bayesian space-time models that allow longitudinal analysis at the zip code level despite frequent boundary redefinitions. These spatial misalignment models control for spatial variation in geographic unit definitions over time and account for spatial autocorrelation using conditional autoregressive (CAR) priors. The model incorporated data from between 1,686 (2005) and 1,693 (2008) zip codes across California for 7 half-year time periods from 2005 through 2008 (n = 11,836).

RESULTS: Density of bars was positively associated with IPV-related ED visits. Density of off-premise outlets was negatively associated with IPV-related ED visits; this association was weaker and smaller than the bar association. There was no association between density of restaurants and IPV-related ED visits.

CONCLUSIONS: Further research is needed to understand the mechanisms by which environmental factors, such as alcohol outlet density, affect IPV behaviors resulting in ED visits.