Objectives: To evaluate the prevalence and correlates of non-fatal overdose among a polysubstance-using cohort of injection drug users (IDU) in Vancouver.
Study design/methods: We evaluated factors associated with non-fatal overdose among participants enrolled in the Vancouver Injection Drug Users Study (VIDUS) using univariate statistics. Self-reports of the awareness of drugs taken and drug potency, polysubstance use, and assistance received at the time of non-fatal overdose were also recorded.
Results: From 1 December 2003 to 1 June 2005, 551 participants who were active injectors were followed. In total, 37 (6.7%) individuals reported experiencing a non-fatal overdose in the previous 6 months. Factors positively associated with non-fatal overdose included public injecting (odds ratio (OR)=4.74, 95% confidence interval (CI) 2.35-9.37, P<0.001), crystal methamphetamine use (OR=4.11) and injection (OR=3.63), morphine injection (OR=3.55), non-injection opiate use (OR=3.30), frequent heroin injection (OR=2.28) and sex trade work (OR=2.12). Factors negatively associated with non-fatal overdose included participation in methadone maintenance therapy (OR=0.31) and injecting alone (OR=0.36). Sixty-two percent of individuals were unaware of drug potency, 64.9% of IDU were taking other drugs at the time of overdosing, with crack being the main drug (37.0%). Fifty-four percent were assisted by ambulance personnel, 56.8% were taken to accident and emergency or hospital, 38.1% left accident and emergency or hospital before being released, and 35.1% were given Naloxone.
Conclusion: Structural interventions are needed that seek to modify the social and contextual risks for overdose, increased access to treatment programmes, and trials of novel interventions for crystal methamphetamine users.