Objectives: The objective of this study was to investigate the potential epidemiological impact of viral load (VL)monitoring and its cost-effectiveness in Vietnam, where transmitted HIV drug resistance (TDR) prevalence hasincreased from <5% to 5%-15% in the past decade.
Methods: Using a population-based mathematical model driven by data from Vietnam, we simulated scenariosof various combinations of VL testing coverage, VL thresholds for second-line ART initiation and availability of HIVdrug-resistance tests. We assessed the cost per disability-adjusted life year (DALY) averted for each scenario.
Results: Projecting expected ART scale-up levels, to approximately double the number of people on ART by 2030,will lead to an estimated 18510 cases (95% CI: 9120-34600 cases) of TDR and 55180 cases (95% CI: 40540-65900 cases) of acquired drug resistance (ADR) in the absence of VL monitoring. This projection corresponds to aTDR prevalence of 16% (95% CI: 11%-24%) and ADR of 18% (95% CI: 15%-20%). Annual or biennial VL monitoringwith 30% coverage is expected to relieve 12%-31% of TDR (2260-5860 cases), 25%-59% of ADR (9620-22650 cases), 2%-6% of HIV-related deaths (360-880 cases) and 19270-51400 DALYs during 2015-30. The30% coverage of VL monitoring is estimated to cost US$4848-5154 per DALY averted. The projected additionalcost for implementing this strategy is US$105-268 million over 2015-30.
Conclusions: Our study suggests that a programmatically achievable 30% coverage of VL monitoring can haveconsiderable benefits for individuals and leads to population health benefits by reducing the overall national burdenof HIV drug resistance. It is marginally cost-effective according to common willingness-to-pay thresholds.