Mortality and causes of death among people who inject amphetamine: A long-term follow-up cohort study from a needle exchange program in Sweden

Background: Abuse of amphetamines is a worldwide problem with around 34 million users, and amphetamine is commonly used by people who inject drugs (PWID). Despite this, there is relatively little research on mortality and cause of death among people who use amphetamines primarily. The present study aimed to examine mortality and causes of death among people who inject amphetamine, and compare these results to the general population. Methods: This retrospective cohort study was based on data from The Malmö Needle Exchange Program in Sweden (MNEP) and on data from The Swedish National Cause of Death Register. Participants in the MNEP, between 1987 and 2011, with registered national identity number and amphetamine as their primary drug of injection use, were included in the study. Standardized mortality ratios (SMR) was calculated for overall mortality and categories of causes of death. Results: 2019 individuals were included (mean follow-up-time 13.7 years [range 0.02–24.2 years], a total of 27,698 person-years). Of the 448 deceased, 428 had a registered cause of death. The most common causes of death were external causes (n = 162, 38%), followed by diseases of the circulatory system (n = 67, 16%). SMR were significantly elevated (8.3, 95% CI [7.5-9.1]) for the entire study population, and for every category of causes of death respectively. Conclusions: People injecting amphetamine as a primary drug were found to have significantly elevated mortality compared with the general population, with high rates of both external and somatic causes of death.