Gender differences in HIV prevalence and all-cause mortality among people who inject drugs (PWID) in Estonia.

Drug overdose and blood-borne viruses (HIV, HCV) are the primary causes of deaths among PWID. In Estonia, studies conducted among PWID have found that more than half of PWID infected with HIV. There are not many studies on mortality and related factors among PWID from countries in Europe that witnessed explosive HIV and HCV epidemics at the beginning of the 2000s.

Retrospective cohort study using data from the community community-based cross-sectional studies in three cities in Estonia from 2013-2018. At the baseline (cross-sectional study recruitment) venous blood was collected and tested for the presence of HIV antibodies. Mortality was identified by linkage to National causes of death registry. Mortality was calculated using person-time methods. Cox regression was used to determine predictors of all-cause mortality. Chi-square test was used to compare gender differences associated with HIV prevalence.

The cohort - a total of 1399 adult PWIDs (75% of men) with the median age of 35 years among men and 32 years among women at baseline. HIV prevalence was 54% among men and 60% among women (p=0.057). Among 1399 participants with 4686,07 person-years of follow-up, 10% were decreased by 2020 (all-cause mortality rate 28.9 per 1 000 person-years (95% CI 25.3-35.3)). Comparison of crude all-cause mortality per 1000 person-years: among men 32.7 (95% CI 27,18-39,24) per 1000 person-years vs 21.6 (95% CI 14,81-31,94) per 1000 person years among women. All-cause mortality among HIV infected men 41.0 (95% CI 32.91-51.15) vs 27.8 (95% CI 17.9-43.0) among HIV infected women. All-cause mortality among HIV uninfected men 22.4 (95% CI 16.06-31.15) vs 12.6 (95% CI 5.7-28.1) among HIV uninfected women. Being HIV infected increased death risk among men (HR=2.0; 95% CI 1.28-3.03; p=0.002), but not among women (HR=2.2; 95% CI 0.82-6.03; p=0.118).

Our study documents that male PWID are not achieving ART treatment benefits. This calls for targeted interventions.