Behavioural, social and structural-level risk factors for developing AIDS among HIV-positive people who use injection drugs in a Canadian setting, 1996-2017.

People who use injection drugs (PWID) experience high rates of HIV acquisition and, as a result of lower rates of optimal access and adherence to combination antiretroviral therapy (ART), experience worse HIV treatment outcomes than other key affected populations. However, the incidence and risk factors for the development of AIDS among HIV-positive PWID have not been completely described. We used data from a community-recruited prospective cohort of HIV-positive PWID in Vancouver, Canada, a setting with universal no-cost ART and a comprehensive clinical monitoring registry. We used multivariable extended Cox models to identify factors associated with time to AIDS. Between 1996 and 2017, 396 participants, including 140 (35.4%) women, were followed for a median of 39.0 months (interquartile range: 16.6-76.2), among whom 165 (41.7%) developed AIDS. In a multivariable model, homelessness (Adjusted Hazard Ratio [AHR] = 1.76 (1.18-2.61)) and injection drug use within the preceding six months (AHR = 1.74 (1.17-2.58)) were independently associated with a higher risk of developing AIDS. Despite widespread scale-up of programmes to improve ART utilization, significant risk factors for the development of AIDS remain among HIV-positive PWID in this setting.