One-year mortality rates of patients receiving methadone and buprenorphine maintenance therapy: a nationally representative cohort study in 2694 patients.

Mortality rates in drug-dependent patients in substitution treatment remain a matter of debate. Although several retrospective toxicological or forensic postmortem studies on this issue have been conducted, few prospective studies have addressed this problem. In a nationally representative sample of 2694 opioid dependent patients in substitution treatment either with methadone or buprenorphine at baseline were monitored over a 12-month period (response rate, 91%). A total number of 1629 (60.4%) were still in treatment after 12 months. The overall mortality rate was 1.04%. In total, 28 patients of the initial sample deceased within the 1-year follow-up period. Eleven (0.4%) of these deaths are due to a fatal intoxication. Three patients (0.1%) died of human immunodeficiency virus/acquired immunodeficiency syndrome, and 3 (0.1%) committed suicide. Thirteen of these patients (4 with overdose/polyintoxication) were not in substitution treatment at the time of death. Other reasons included accidents and deaths due to other medical conditions. Only in one case the reason could not be ascertained. The mortality rate was similar in methadone as compared with buprenorphine patients. Taking into account the high comorbidity of opioid dependent patients and the severity of dependence, the mortality rate of approximately 1% confirms that maintenance treatment could be regarded as a fairly safe treatment.