Ongoing impact of HIV infection on mortality among people who inject drugs despite free antiretroviral therapy.

Abstract

To determine the impact of HIV infection on mortality over time among people who inject drugs (PWID) in settings with free HIV/AIDS care. Prospective cohort study of PWID in Vancouver, Canada, recruited between May 1996 and December 2011. We ascertained morality rates and causes of death through a confidential linkage with the provincial vital statistics registry. A total of 2283 individuals were followed for a median of 60.9 months (interquartile range: 34.4-113.1), among whom 622 (27.2%) individuals were HIV-positive at baseline, and 179 (7.8%) seroconverted during follow-up. The primary and secondary outcomes of interests were all-cause mortality and cause of death, respectively. The main independent variable of interest was HIV serostatus (positive versus negative). We used Cox proportional hazards regression to determine factors associated with mortality, including socio-demographic variables, drug use behaviors and other risk behaviors. During the study period, 491 (21.5%) individuals died. In multivariate analyses, HIV infection remained associated independently with all-cause mortality (adjusted hazard ratio = 3.15; 95% CI: 2.59-3.82). While all-cause mortality rates declined markedly during the study period (P < 0.001), the independent effect of HIV infection on mortality remained unchanged over time (P = 0.640). Among HIV-positive individuals, significant changes in causes of death from infectious and AIDS-related causes to non-AIDS-related etiologies were observed. HIV infection continues to have a persistent impact on mortality rates among people who inject drugs in settings with free HIV/AIDS care, although causes of death have shifted markedly from infectious and AIDS-related causes to non-AIDS-related etiologies.