Effectiveness of diacetylmorphine versus methadone for the treatment of opioid dependence in women.

Background: There is consistent evidence showing women access treatment with more severe substance-related profiles relative to men; however, treatment outcome evaluation shows inconclusive results regarding gender differences. Furthermore, few studies evaluate response by gender.

Methods: The present analyses were performed using data from the NAOMI study, an open-label, phase III randomized controlled trial, carried out between 2005 and 2008 in Vancouver and Montreal, Canada. A total of 226 long-term treatment-refractory opioid dependent individuals were randomized to receive injectable diacetylmorphine or oral methadone for 12 months. Patients in both treatment groups were offered psychosocial and primary care services. Main outcomes were retention in addiction treatment at 12 months. Drug use, health, psychosocial adjustment and health-related quality of life were examined at baseline and during treatment, using the European Addiction Severity Index, Maudsley Addiction Profile, SF-6D and EuroQol EQ-5D.

Results: A total of 88 (38.9%) females and 138 (61.1%) males were included in the present analysis. Retention rates among female participants in the diacetylmorphine group were significantly higher than oral methadone (83.3% vs. 47.8%). Males receiving diacetylmorphine improved significantly more than females in physical health, health-related quality of life, and family relations but female participants in the diacetylmorphine group had significantly greater improvements in illicit drug use scores and psychological health compared to females allocated to oral methadone.

Conclusions: Among long-term opioid dependent women who have not benefited sufficiently from available treatments, medically prescribed diacetylmorphine is more effective than oral methadone. Men receiving diacetylmorphine showed more improvements than women.