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

Abstract

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. 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. 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. 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.