Six-Year Outcome of Opioid Maintenance Treatment in Heroin-Dependent Patients: Results from a Naturalistic Study in a Nationally Representative Sample.

BACKGROUND In many countries, the opioid agonists, buprenorphine and methadone, are licensed for maintenance treatment of opioid dependence. Many short-term studies have been performed, but little is known about long-term effects. Therefore, this study described over 6 years (1) mortality, retention and abstinence rates and (2) changes in concomitant drug use and somatic and mental health. METHODS A prevalence sample of n = 2,694 maintenance patients, recruited from a nationally representative sample of n = 223 substitution doctors, was evaluated in a 6-year prospective-longitudinal naturalistic study. At 72 months, n = 1,624 patients were assessed for outcome; 1,147 had full outcome data, 346 primary outcome data and 131 had died; 660 individuals were lost to follow-up. RESULTS The 6-year retention rate was 76.6%; the average mortality rate was 1.1%. During follow-up, 9.4% of patients became "abstinent" and 1.9% were referred for drug-free addiction treatment. Concomitant drug use decreased and somatic health status and social parameters improved. CONCLUSIONS The study provides further evidence for the efficacy and safety of maintenance treatment with opioid agonists. In the long term, the number of opioid-free patients is low and most patients are more or less continuously under opioid maintenance therapy. Further implications are discussed.