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


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.


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
Mark A
MA
Centre for Epidemiology and Population Health Research, Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia. stoove@burnet.edu.au
Dietze
Paul M
PM
Jolley
Damien
D
D000328:Adult; D000367:Age Factors; D000552:Ambulances / Q000706:statistics & numerical data; D015331:Cohort Studies; D003644:Death Certificates; D062787:Drug Overdose / Q000401:mortality; D005260:Female; D003932:Heroin / Q000506:poisoning*; D006556:Heroin Dependence / Q000453:epidemiology / Q000401:mortality*; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D015819:Substance Abuse, Intravenous / Q000401:mortality*; D014739:Victoria / Q000453:epidemiology; D055815:Young Adult
D003932:Heroin