Modeling the health impact and cost threshold of long-acting ART for adolescents and young adults in Kenya

BACKGROUND: Despite high efficacy of oral antiretroviral therapy (ART), viral suppression among adolescents and young adults (AYA) living with HIV in sub-Saharan Africa (SSA) remains low. Compared to daily oral ART, bimonthly long-acting injectable ART (LA-ART) may simplify adherence, improve clinical outcomes, and decrease HIV transmission in this priority population. However, LA-ART will likely cost more than oral ART and the cost threshold at which LA-ART will be cost effective in SSA has not been evaluated. METHODS: We adapted a mathematical model of HIV transmission and progression in Kenya to include HIV acquisition and viral suppression among AYA (age 10–24). We projected the population-level health and economic impact of providing LA-ART to AYA over a 10-year time horizon assuming oral ART costs of US$233 annually and a two-month duration of viral suppression per LA-ART injection. We calculated the maximum cost at which switching from oral to LA-ART would be considered cost-effective, using thresholds of $500 and $1,508 per disability-adjusted life year averted (WHO's threshold of HIV treatment interventions and Kenya's gross domestic product per capita). FINDINGS: Assuming 85% of AYA switch from oral to injectable formulations, LA-ART is estimated to prevent 40,540 infections and 20,480 deaths over 10 years. The maximum increase in the annual per-person cost of receiving LA-ART is estimated to be $89 and $236 for LA-ART to be cost-effective under the thresholds of $500 and $1,508 per DALY averted, respectively. The cost threshold was lower when non-adherent oral ART AYA users were assumed to be less likely to switch to LA-ART. INTERPRETATION: Providing LA-ART to AYA can be cost-effective in Kenya if it is less than twice the cost of oral ART. Long-acting injectable ART for priority populations with low viral suppression has the potential to cost-effectively avert disability and death. FUNDING: National Institutes of Health (R01 HD085807; PI: Kohler)