Problem Drinking and Marijuana Use as Risks for Unidirectional and Bidirectional Partner Violence.

Despite evidence that most who perpetrate intimate partner violence (IPV) also report victimization, little is known about bidirectional IPV among Emergency Department (ED) patients and its association with problem drinking and marijuana use. We conducted an observational, cross-sectional survey among low- and moderate-acuity patients at a Northern California safety-net ED. Physical IPV was measured with the Revised Conflict Tactics Scale (CTS2). We recorded patient's frequency of intoxication and marijuana use. Spouse/partner's problem drinking and marijuana use were measured dichotomously. Odds Ratios [ORs] and 95% confidence intervals [CIs] were estimated using multinomial logistic regression models of unidirectional and bidirectional IPV. Among 1,037 patients (53% female), perpetration only, victimization only, and bidirectional IPV were reported by 3.8%, 6.2%, and 13.3% of the sample, respectively. Frequency of intoxication was associated with perpetration (OR 1.50; 95% CI 1.18 to 1.92) and bidirectional IPV (OR=1.34; 95% CI 1.13 to 1.58). Days of marijuana use were associated with bidirectional IPV (OR=1.15; 95% CI 1.03 to 1.28). Patients whose partners were problem drinkers were at risk for victimization (OR=2.56; 95% CI=1.38, 4.76) and bidirectional IPV (OR=1.97; 95% CI 1.18, 3.27). Among patients who reported any past-year IPV, most experienced bidirectional aggression. ED staff should consider asking patients who are married, cohabiting, or in a dating relationship about their experience with past-year IPV and inquire about their substance use patterns and those of their romantic partner, to share information about potential linkages. Medical and recreational marijuana legalization trends underscore the importance of further research on IPV and marijuana.