Heavy alcohol use and suicidal behavior among people who use illicit drugs: A cohort study

Background: People who use illicit drugs (PWUD) are known to experience high rates of suicidal behavior. While heavy alcohol use has been associated with suicide risk, its impact on the suicidal behavior of PWUD has not been well characterized. Therefore, we examined the relationship between heavy alcohol use and suicidal behavior among PWUD in Vancouver, Canada. Methods: Data are derived from two prospective cohort studies of PWUD in Vancouver, Canada, from 2005 to 2013. Participants completed questionnaires that elicited information regarding sociodemographics, drug use patterns, and mental health problems, including suicidal behavior. We used recurrent event survival analyses to estimate the independent association between at-risk/heavy drinking (based on National Institute of Alcohol Abuse and Alcoholism [NIAAA] criteria) and risk of incident, self-reported suicide attempts. Results: Of 1757 participants, 162 participants (9.2%) reported 227 suicide attempts over the 8-year study period, resulting in an incidence rate of 2.5 cases per 100 person-years. After adjusting for potential confounders, including intensive illicit drug use patterns, heavy alcohol use (adjusted hazard ratio [AHR] = 1.97; 95% confidence interval [CI] = 1.39, 2.78) was positively associated with an increased risk of suicidal behavior. Conclusions: We observed a high burden of suicidal behavior among a community-recruited sample of PWUD. Heavy alcohol use predicted a higher risk of suicide attempt, independent of other drug use patterns. These findings demonstrate the need for evidence-based interventions to address suicide risk among PWUD, particularly those who are heavy consumers of alcohol. (C) 2015 Elsevier Ireland Ltd. All rights reserved.