Overdose deaths following previous non-fatal heroin overdose: Record linkage of ambulance attendance and death registry data

Introduction and Aims. Experiencing previous non‐fatal overdoses have been identified as a predictor of subsequent non‐fatal overdoses; however, few studies have investigated the association between previous non‐fatal overdose experiences and overdose mortality. We examined overdose mortality among injecting drug users who had previously been attended by an ambulance for a non‐fatal heroin overdose. Design and Methods. Using a retrospective cohort design, we linked data on non‐fatal heroin overdose cases obtained from ambulance attendance records in Melbourne, Australia over a 5‐year period (2000–2005) with a national death register. Results. 4884 people who were attended by ambulance for a non‐fatal heroin overdose were identified. One hundred and sixty‐four overdose deaths occurred among this cohort, with an average overdose mortality rate of 1.20 per 100 person‐years (95% CI, 1.03–1.40). Mortality rate decreased 10‐fold after 2000 coinciding with widely reported declines in heroin availability. Being male, of older age (>35 years) and having been attended multiple times for previous non‐fatal overdoses were associated with increased mortality risk. Discussion and Conclusions. As the first to show a direct association between non‐fatal overdose and subsequent overdose mortality, this study has important implications for the prevention of overdose mortality. This study also shows the profound effect of macro‐level heroin market dynamics on overdose mortality.[Stoové MA, Dietze PM, Jolley D. Overdose deaths following previous non‐fatal heroin overdose: Record linkage of ambulance attendance and death registry data. Drug Alcohol Rev 2009;28:347–352]