Non-fatal heroin overdose, treatment exposure and client characteristics: Findings from the Australian Treatment Outcome Study (ATOS)

The relationship between treatment exposure, drug use, psychosocial variables and non- fatal heroin overdose was examined among a cohort of 495 heroin users, re- interviewed at 12 months. The 12- month overdose rate declined from 24% to 12%, and the proportion administered naloxone declined from 15% to 7%. There were significant reductions in overdose among those who entered maintenance therapies ( 22% to 4%) and residential rehabilitation ( 33% vs. 19%) at baseline, but not among those who entered detoxification or were not entering treatment. The total number of treatment days received over the follow- up period was associated independently with a reduced risk of overdose. Each extra treatment day was associated with a 1% reduction in risk of overdose over the follow- up period. By contrast, more treatment episodes were associated with an increased risk of overdose ( OR 1.62). Other independent predictors of overdose over follow- up were more extensive polydrug use ( OR 1.40), and having overdosed in the year preceding the study ( OR 7.87).