Publications & Reports

Mortality in the SuperMIX cohort of people who inject drugs in Melbourne, Australia: A prospective observational study.

Hill PL, Stoové M, Agius PA, Maher L, Hickman M, Crawford S, Dietze P.
Burnet Institute, Behaviours and Health Risks, Melbourne, VIC, Australia.


AIMS: To measure mortality rates and factors associated with mortality risk among participants in the SuperMIX study, a prospective cohort study of people who inject drugs. DESIGN: A prospective observational study using self-reported behavioural and linked mortality data. SETTING: Melbourne, Australia. PARTICIPANTS/CASES: A total of 1209 people who inject drugs (67% male) followed-up between 2008-2019 for 6913 person years (PY). MEASUREMENTS: We linked participant identifiers from SuperMIX to the Australian National Death Index and estimated all-cause and drug-related mortality rates and standardized mortality ratios (SMRs). We used Cox regression to examine associations between mortality and fixed and time-varying sociodemographic, alcohol and other drug use, and health service-related exposures. FINDINGS: Between 2008 and 2019 there were 76 deaths in the SuperMIX cohort. Of those with a known cause of death (n=68), 35 (51%) were drug related, yielding an all-cause mortality rate of 1.1 per 100PY (95% confidence interval [CI] 0.88-1.37) with an estimated SMR of 16.64 (95%CI 13.29-20.83), and overall accidental drug-induced mortality rate of 0.5 per 100 PY (95%CI 0.36-0.71). Reports of recent use of ambulance services (adjusted hazard ratio [AHR]=3.77, 95%CI 1.78-7.97) and four or more incarcerations (AHR=2.78, 95%CI 1.55-4.99) were associated with increased mortality risk. CONCLUSIONS: In Melbourne, Australia, mortality among people who inject drugs appears to be positively associated with recent ambulance attendance and experience of incarceration.

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