Factors associated with 12 months continuous heroin abstinence: findings from the Australian Treatment Outcome Study (ATOS)

Aims: To determine the role of treatment and client characteristics associated with the achievement of continuous heroin abstinence. Design: Longitudinal cohort study. Setting: Sydney and Adelaide, Australia. Participants: 570 heroin users re-interviewed at 12 month follow-up for the Australian Treatment Outcome Study (ATOS). Findings: Continuous heroin abstinence was reported by 14% of participants. Continuous abstinence was associated with no previous treatment history, having entered treatment at baseline, and cumulative treatment exposure over the follow-up period. Longer retention times in index maintenance and residential rehabilitation treatments, but not detoxifications, were most associated with abstinence. At baseline, abstinent participants were more likely to have been classified as treatment ready, or to have used heroin less frequently; and less likely to have been daily injectors, using cocaine or criminally involved. Conclusions: Approximately 14% of ATOS participants achieved continuous heroin abstinence over 12 months. Such an achievement was strongly associated with a longer “dose” of treatment, and with more treatment stability over the follow-up period.