Recent non-fatal opioid overdose: the effects of health service utilisation, alcohol and other drug use and demographic factors

Background

Opioid overdose is a major public health problem globally, with overdose incidence and mortality increasing at rapid rates in North America, and similar trends emerging associated with morbidity and mortality in Australia. Many people who inject drugs (PWID) are at risk of opioid overdose. In this study we use data from the SuperMIX study, a cohort of younger PWID that has been running since 2008, to identify the incidence and predictors of non-fatal opioid overdose of PWID in Melbourne.

Methods

The incidence of overdose throughout the study period was calculated from SuperMIX cohort data from PWID recruited between 2008 and 2018. Rates of first overdose overall and disaggregated by follow-up interview were obtained. Associations between these outcomes and health service use, alcohol and other drug characteristics and sociodemographic characteristics were examined using multivariate logistic regression.

Results

The cohort of 637 participants contributed 3317 person-years from recruitment to 2019. Over a quarter (26.7%) of participants reported opioid overdose throughout the follow-up period, yielding an overdose rate of 5.1 events per 100 person-years. Reports of recent opioid overdose were significantly associated with high frequency of alcohol consumption (4+ times a week) (AOR: 1.73, p=0.002, 95%CI: 1.23-2.43), self-reported severe pain (AOR: 1.99, p=0.001, 95%CI=1.34-2.96), history of incarceration (AOR: 1.65, p=0.001, 95%CI: 1.22-2.24), recent crystal methamphetamine injection (AOR: 3.40, p=0.021, 95%CI: 1.20-9.60); and significantly negatively associated with the participant being currently on opiate substitution treatment (AOR: 0.61, p<0.001, 95%CI: 0.48-0.79).

Conclusions

Significant associations were found between higher weekly frequency of alcohol consumption, self-reported severe pain, history of incarceration, recent crystal methamphetamine injection and current use of opiate substitute treatment. Our findings underscore the importance of further research into recent predictors of opioid overdose and investigation of longitudinal patterns of opioid overdose.