Injection methamphetamine use is associated with an increased risk of attempted suicide: a prospective cohort study.

BACKGROUND: Methamphetamine (MA) use is a growing public health concern in many settings around the world. While some physical and mental health effects associated with injection MA use have been well described, little is known about the relationship between injecting MA and suicidal behavior. We sought to determine whether MA injection was associated with an increased risk of attempting suicide among a prospective cohort of injection drug users (IDUs) in Vancouver, Canada.
METHODS: Between 2001 and 2008, eligible participants enrolled in the Vancouver Injection Drug Users Study (VIDUS) completed semi-annual questionnaires that elicited information regarding sociodemographics, drug use patterns, and mental health problems including suicidal behavior. We used Cox proportional hazards models with time-dependent covariates to determine whether self-reported MA injection was an independent predictor of attempting suicide at subsequent time points.
RESULTS: Of 1873 eligible participants, 149 (8.0%) reported a suicide attempt, resulting in an incidence density of 2.5 per 100 person-years. Participants who attempted suicide were more likely to be younger (median: 35 vs. 40, p<0.01), female (48.3% vs. 35.1%, p<0.01), and of Aboriginal ancestry (43.6% vs. 31.3%, p<0.01). In a Cox proportional hazards model, MA injection was associated with an 80% increase in the risk of attempting suicide (adjusted hazard ratio=1.80, 95% CI: 1.08-2.99, p=0.02).
CONCLUSIONS: These findings suggest that IDUs who inject MA should be monitored for suicidal behavior. Improved integration of mental health and suicide prevention interventions within harm reduction and drug treatment programs may be fruitful.