Patterns and Predictors of Heroin Use, Remission, and Psychiatric Health Among People with Heroin Dependence: Key Findings from the 18–20-Year Follow-Up of the Australian Treatment Outcome Study (ATOS)

This study aimed to investigate the long-term patterns and predictors of heroin use, dependence, and psychiatric health over 18–20 years among a cohort of Australians with heroin dependence, using a prospective longitudinal cohort study conducted in Sydney, Australia. The original cohort consisted of 615 participants, who were followed up at 3 months and 1, 2, 3, 11, and 18–20 years post-baseline; 401 (65.2%) were re-interviewed at 18–20 years. The Australian Treatment Outcome Study structured interview with established psychometric properties was administered to participants at each follow-up, addressing demographics, treatment and drug use history, overdose, crime, and physical and mental health. Overall, 96.7% completed at least one follow-up interview. At 18–20 years, 109 participants (17.7%) were deceased. Past-month heroin use decreased significantly over the study period (from 98.7 to 24.4%), with one in four using heroin at 18–20 years. Just under half were receiving treatment. Reductions in heroin use were accompanied by reductions in heroin dependence, other substance use, needle sharing, injection-related health, overdose, crime, and improvements in general physical and mental health. Major depression and borderline personality disorder (BPD) were consistently associated with poorer outcome. At 18–20 years, there is strong evidence that clinically significant levels of improvement can be maintained over the long term. The mortality rate over 18–20 years was devastating, with over one in six participants deceased. More sustained and targeted efforts are needed in relation to major depression and BPD to ensure evidence-based treatments are delivered to people with heroin dependence.