Mortality among people who inject drugs - the interwoven roles of fentanyl and HIV: a community-based cohort study

Background: Excess all-cause mortality is a key indicator for assessing direct and indirect consequences of injection drug use and data are warranted to delineate sub-populations within people who inject drugs at higher risk of death. Our aim was to examine mortality and factors associated with mortality among people who inject drugs in Estonia. Methods: Retrospective cohort study using data from people who inject drugs recruited in the community with linkage to death records. Standardized mortality ratios were used to compare the cohort mortality to the general population and potential predictors of death were examined through survival analysis (Cox regression). The cohort include a total of 1399 people who inject drugs recruited for cross-sectional surveys using respondent driven sampling between 2013 and 2018 in Estonia. A cohort with follow-up through 2019 was formed with linkage to national causes of death registry. Results: Among 1399 participants with 4684 person-years of followup, 10% were deceased by 2019. The all-cause mortality rate in the cohort was 28.9 per 1000 person-years (95% confidence interval 25.3-35.3). Being HIV positive, injecting mainly opioids (fentanyl), living in the capital region and the main source of income other than work were associated with greater mortality risk. Conclusions: While low-threshold services have been available for a long time for people who inject drugs, there is still a need to widen the availability and integration of services, particularly the integration of HIV and opioid treatment.