Building a Decision Model to Estimate the Health and Economic Benefits of Targeted Mental Health Interventions to Improve ART Adherence among Young People Living with HIV in Tanzania

Young people living with HIV (YPLWH) constitute a growing proportion of the global population of people living with HIV but have less access to HIV testing, diagnosis, treatment, and face heightened mental health challenges. To address these challenges, targeted mental health and medication adherence interventions have been developed, including in Tanzania, which is home to 6% of the world's YPLWH. This study proposes a mathematical model to estimate the health and economic outcomes of mental health HIV adherence interventions targeting YPLWH in Tanzania.We developed a Markov model to predict the long-term health (Disability-Adjusted Life Years (DALY)) and economic outcomes (Value of a Statistical Life Year (VLSY)) of mental health HIV adherence interventions targeting YPLWH. We parameterized the model using outcomes data from the 2016-2020 Sauti ya Vijana randomized control trial (RCT) conducted in Moshi, Tanzania. Cost data were retrieved from a cost analysis of the same RCT and supplemented with data from published literature. The study is conducted from a health payer’s perspective, and the Willingness-To-Pay (WTP) per DALY averted was set to the 2021 Tanzanian GDP per capita (USD 1099.3). Costs and outcomes were modeled for ten years and discounted at an annual rate of 3%. The findings suggest that the Sauti ya Vijana intervention modeled in this study is cost-effective at a WTP of USD 1099.3. The Incremental cost-effectiveness ratio for the intervention compared to the standard of care was USD 637.06 per DALY averted at a 3% discount rate. The benefit-to-cost ratio of the intervention was USD 26.54 in economic productivity for the intervention arm for every dollar spent on the intervention, and the net economic productivity benefit was USD 17,174.74 over a decade. Mental health adherence interventions hold the promise of improving health outcomes amongst YPLWH. The mathematical model developed in this study is a valuable decision-making tool for policymakers regarding mental health adherence interventions targeting YPLWH in Tanzania. The model contributes to the global goal of achieving the UNAIDS 95-95-95 targets for YPLWH.