Stimulant Use Interventions May Strengthen ‘Getting to Zero’ Initiatives in Illinois: Insights from a Modeling Study

Abstract

Objective(s): Young Black men who have sex with men (YBMSM) are a key population identified in the Illinois Getting to Zero (GTZ) initiative who have experienced disproportionate HIV incidence. Rising stimulant use has been determined to impede the effectiveness of ART and pre-exposure prophylaxis for suppressing HIV transmission in populations. This modeling study explores the impact of stimulant use on HIV incidence among YBMSM, given the limited development of dedicated or culturally appropriate interventions for this population, and assesses the impact of these interventions on downstream HIV transmission in the context of achieving GTZ goals. Methods: A previously developed agent-based network model (ABNM), calibrated using data for YBMSM in Illinois, was extended to incorporate the impact of stimulant use (methamphetamines, crack/cocaine, and ecstasy) on sexual networks and engagement in HIV treatment and prevention continua. The model simulated the impact of a residential behavioral intervention (BI) for reducing stimulant dependency and an outpatient biomedical intervention (mirtazapine) for treating methamphetamine dependence on improved engagement in the HIV treatment and prevention continua. The downstream impact of these interventions on population-level HIV incidence was the primary intervention outcome. Results: Baseline simulated annual HIV incidence in the ABNM was 6.9(95% CI: 6.83,7.04) per 100 person years (py) and 453 (95% CI: 445.9,461.2) new infections annually. A residential targeted to 25% of stimulant users yielded a 27.1% decline in the annual number of new infections. Initiating about 50% of methamphetamine users on mirtazapine reduced the overall HIV incidence by about 11%. A 25% increase in antiretroviral treatment (ART) and preexposure prophylaxis (PrEP) uptake in the non-stimulant using YBMSM population combined with a 25% uptake of BI for stimulant users produces an HIV incidence consistent with HIV elimination targets (about 200 infections/year) identified in the GTZ initiative. Conclusions: Targeted behavioral and biomedical interventions to treat stimulant dependency are likely to provide additive benefits to expanding ART and PrEP uptake for everyone in accomplishing GTZ initiatives for HIV elimination.