Social and structural barriers to effective antiretroviral therapy for HIV infection among injection drug users

Background: Despite the development of antiretroviral therapy (ART), injection drug users (IDU) continue to have high levels of HIV-related morbidity and mortality. This thesis sought to apply the risk environment conceptual framework on patterns of HIV treatment outcomes by: Systematically reviewing the epidemiologic literature on HIV disease progression among illicit drug users; examining the incidence of viral rebound among IDU on ART; evaluating the role of homelessness on the suppression of plasma HIV RNA viral load; and assessing the role of incarceration on the likelihood of non-adherence to ART. Methods: HIV-seropositive IDU participating in an ongoing prospective observational cohort completed biannual interviewer-administered questionnaires. This data was confidentially linked to comprehensive records on HIV treatment and related clinical outcomes held by a clinical monitoring laboratory and antiretroviral dispensary. A variety of longitudinal analytic techniques were used to estimate the independent relationships between selected social- and structural-level exposures and the outcomes of interest while controlling for relevant sociodemographic, clinical and behavioural factors. Results: The systematic review found that only a minority of studies included social- and structural-level measures in analyses of disease progression and treatment outcomes. Longitudinal analysis of viral rebound found that incarceration and sex trade involvement were significantly associated with higher rates. Among individuals initiating ART, homelessness was a significant structural barrier to suppression. Among individuals prescribed ART, we observed a dose-dependent relationship between non-adherence and the number of incarceration episodes. Conclusions: In this setting of free and universal access to HIV care and ART, sub-optimal treatment outcomes were common among IDU. Consistent with an application of the HIV risk environment, a number of prevalent social- and structural-level exposures were associated with higher risks of non-adherence to treatment and poorer treatment outcomes, including homelessness, sex trade involvement and incarceration. Interventions to reduce elevated levels of preventable HIV-related morbidity and mortality among IDU should consider the role played by modifiable aspects of the HIV risk environment.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat