Injecting and noninjecting heroin administration : transitions and treatment outcome across 36 months

To examine long-term stability in route of administration and treatment outcomes for noninjecting (NIHU) and injecting (IHU) heroin users, a cohort of 429 heroin users were followed over 36 months. Across follow-up, 35.3% of NIHU injected heroin and a transition to primary heroin injecting was made by 8.5%. Amongst IHU, 11.1% smoked heroin and a transition to primary heroin smoking was made by 2.3%. While NIHU were less likely to be in treatment at 36 months, there were no differences in overall treatment exposure. At 36 months, there were no differences in heroin use, polydrug use, crime, physical health, or psychopathology. NIHU were, however, less likely to be injecting and to have injection-related health problems. It is concluded that there is a substantial risk of injecting occurring amongst NIHU and that route of administration does not differentially predict long-term treatment response.