Causes of premature mortality in Swedish drug abusers: a prospective longitudinal study 1970-2006.

Aims: To evaluate premature mortality and causes of death from young adulthood to middle age in a cohort of drug users followed during almost four decades.

Design: Follow-up study of a consecutive cohort of patients with drug abuse/dependence.

Methods: A cohort of 561 drug abusers, admitted to a detoxification and short-term rehabilitation unit 1970-1978 was followed to December 31st, 2006. Standardized interviews and hospital records with toxicological analyses were used for demographic data, substance use and psychiatric diagnoses at admission. For Follow-up analyses, autopsy protocols including toxicology tests and death certificates were obtained for assessment of causes of death which were coded according to ICD-10. Age-group standardized mortality ratios were calculated independently for both sexes.

Results: 204 persons (36.4%) were deceased by 2006. SMR was 5.94 for the cohort. Compared to an age- and gender-matched population, the risk of premature death was about eighteen times higher between the ages of 20-44 and about five times higher from 45 up to the age of 69. Of 120 (59%) drug-related deaths, 43 were opiate overdoses, and 3 were overdose from amphetamine. A total of 53 (26%) persons died violent deaths: 39 suicides, of which 25 were drug-related, 3 homicides and 12 accidents. The Swedish national causes of death register underestimated drug-related death by 37% and suicide by 85% compared to the results from this study.

Conclusions: The cohort of drug abusers had an increased risk of premature often drug-related and violent death well into middle age, and to a great extent the drug addicts died from the same drug they had abused when they were first admitted for treatment. The underestimation of drug-related death and suicide in some national death cause registers could be reduced if the doctor routinely records ICD codes when issuing death certificates and autopsy protocols.