Longitudinal associations of substance use severity and antiretroviral therapy adherence among people with HIV

Thesis (Master's)--University of Washington, 2022Purpose: Substance use is associated with lower antiretroviral therapy (ART) adherence and subsequent negative effects on HIV suppression. We examined longitudinal associations of substance use severity and number of substances used with ART adherence in the current ART era.Setting/Methods: We evaluated all adult people with HIV (PWH) in the Centers for AIDS Research Network of Integrated Clinical Sites cohort with ≥2 self-reported ART adherence measurements in 2010-2021. Participants completed longitudinal assessments for substance use severity (modified AUDIT-C [alcohol]; modified ASSIST [marijuana, illicit drugs including methamphetamine, cocaine/crack, illicit opioids]) and ART adherence (visual analog scale). Adjusted linear mixed models were used to examine longitudinal associations of ART adherence with time-varying substance use severity and number of substances used. Results: Among 10557 PWH in care, alcohol (68%) and marijuana (33%) were the most reported substances; methamphetamine (9%) was the most reported illicit drug; and polysubstance use was common (32% ≥2 substances). More severe substance use across all substances and higher self-reported number of substances used were associated with lower ART adherence. Methamphetamine use was associated with the greatest declines in adherence ranging from 3.05% with low severity use (95% confidence interval [CI] -4.23, -1.87) to 10.77% with high severity use (95% CI -12.76, -8.78). Conclusion: Severe substance use among PWH, especially methamphetamine, was associated with meaningful declines in adherence in the modern era of ART. Our findings warrant expansion of multidisciplinary, integrated care models and further research into new therapies, especially for methamphetamine, to improve ART adherence and downstream HIV outcomes