"Of the 6,640 patients in the OST programme in Norway at the end of 2011, 54 deaths from various causes were reported by the centres during 2011, indicating a total mortality rate of about 0.8 per 100 patient-years while in OST. This is on par with the previous year (Table 4). The majority of deaths in OST were due to somatic causes and injuries.
"It is generally accepted that the annual mortality rate among untreated injecting heroin users is in the range of two to four per cent. In a study of Norwegian OST programme participants for the period 1997–2003, an annual mortality rate of 2.4 per cent was found prior to treatment, and 3.5 per cent post-treatment among those who terminated OST. In the same study, the annual mortality rate was 1.4 per cent for those in active OST. For patients in active OST, causes of death were: somatic causes 55 per cent, overdoses 27 per cent and trauma 18 per cent, whereas, for the observed times prior to and after OST, overdoses dominated as the cause of death. The annual mortality rate for patients in OST has gradually decreased in Norway since 2002, from an estimated 1.5 per cent to a current rate of 0.8 per cent."


Norwegian Institute for Alcohol and Drug Research, "The Drug Situation in Norway 2012: annual report to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)," (Oslo, Norway: December 2012), p. 37.