Patterns and correlates of non-fatal heroin overdose at 11-year follow-up: findings from the Australian Treatment Outcome Study

Abstract

Background: Overdose is a major cause of morbidity and mortality amongst opioid users. This paper reported recent non-fatal overdose amongst the Australian Treatment Outcome Study (ATOS) cohort at 11-year follow-up, and characteristics that predict recent overdose.

Methods: Longitudinal cohort, with 431 (70.1%) of the original 615 participants interviewed. Participants were administered the ATOS structured interview, addressing demographics, treatment history, drug use, heroin overdose, criminality, health and psychopathology.

Findings: Mean time since heroin initiation was 20.4 years. By 11-year follow-up, the proportion who had overdosed was 67.5%, and 24.4% had experienced five or more overdoses. In the 12 months preceding 11-year follow-up, 4.9% had overdosed (11.8% of those who had used heroin in that period). Of the 21 participants who had recently overdosed, 20 (95.2%) had overdosed previously, and 19 (90.5%) were not enrolled in a treatment programme at the time. Those who had recently overdosed reported higher levels of use of opiates other than heroin (57.1% vs 24.9%), benzodiazepines (61.9% vs 30.5%,), methamphetamine (38.1% vs 16.8%) and cocaine (19.0% vs 3.7%). They also had exhibited higher levels of heroin use and other drug use at baseline, 12 and 24 month follow-ups.

Conclusions: While the prevalence had declined, overdoses still occurred. A history of overdose and polydrug use patterns continued to provide strong markers for those at continued risk.

Keywords: Cohort; Correlates; Heroin; Longitudinal; Overdose.