Cost-effectiveness of implementing HIV and HIV/syphilis dual testing among key populations in Viet Nam: a modeling analysis

ABSTRACT Objectives Key populations, including sex workers, men who have sex with men, and people who inject drugs, have a high risk of HIV and sexually transmitted infections (STIs). We assessed the health and economic impacts of different HIV and syphilis testing strategies among three key populations in Viet Nam using a dual HIV/syphilis rapid diagnostic test (RDT). Setting We used the Spectrum AIDS Impact Model to simulate the HIV epidemic in key populations in Viet Nam and evaluated five testing scenarios. We used a 15-year time horizon and all costs are from the provider’s perspective. Participants We include the entire population of Viet Nam in the model. Interventions We model five testing scenarios among key populations: 1) annual testing with an HIV rapid diagnostic test (RDT), 2) annual testing with a dual RDT, 3) biannual testing using dual RDT and HIV RDT, 4) biannual testing using HIV RDT, and 5) biannual testing using dual RDTs. Primary and secondary outcome measures The primary outcome is incremental cost-effectiveness ratios (ICERS). Secondary outcomes include HIV and syphilis cases and costs for each proposed intervention. Results Annual testing using a dual HIV/syphilis RDT was cost saving and averted 3,206 HIV cases and treated 7,719 syphilis cases compared to baseline over 15 years. Biannual testing using one dual test and one HIV RDT, or two dual tests both averted an additional 875 HIV cases and were cost-effective ($1,024 and $2,518 per DALY averted, respectively). Annual or biannual HIV testing using HIV RDTs and separate syphilis tests were more costly and less effective than using one or two dual RDTs. Conclusions Annual or biannual HIV and syphilis testing using dual RDTs among key populations can be cost-effective and support countries in reaching global reduction goals for HIV and syphilis. STRENGTHS AND LIMITATIONS OF THIS STUDY Strength: Our model presents novel cost-effectiveness estimates for the use of dual HIV/syphilis testing in key populations that can inform health planners Strength: We include five testing scale up scenarios using both HIV RDT and dual HIV/syphilis RDT Strength: Our model is informed by demographic, behavioral, and biological data from government sources, surveys, surveillance, publicly available reports, databases, and peer-reviewed literature Limitation: We made some assumptions regarding the timing and uptake of HIV and syphilis testing among key populations that may be inaccurate. Limitation: Our model assumes that increased syphilis testing and treatment will not impact syphilis prevalence, however, it is unknown whether increased testing will reduce or increase syphilis prevalence.