RESUMO
BACKGROUND: Substantial gaps remain in understanding the trade-offs between the costs and benefits of choosing alternative human immunodeficiency virus (HIV) prevention strategies, including test-and-treat (expanded HIV testing combined with immediate treatment) and PrEP (initiation of preexposure prophylaxis by high-risk uninfected individuals) strategies. METHODS: We develop a mathematical epidemiological model to simulate HIV incidence among men residing in Los Angeles County, California, aged 15-65 years, who have sex with men. We combine these incidence data with an economic model to estimate the discounted cost, effectiveness (quality-adjusted life-years [QALYs]), and incremental cost-effectiveness ratios of various HIV prevention strategies using a societal perspective and a lifetime horizon. RESULTS: PrEP and test-and-treat yield the largest reductions in HIV incidence, and are highly cost-effective ($27 863/QALY and $19 302/QALY, respectively) relative to status quo and at a US willingness-to-pay threshold of $150 000/QALY saved. Status quo and 12 test-and-treat and PrEP strategies determine the frontier for efficient decisions. More aggressive strategies are costlier, but more effective, albeit with diminishing returns. The relative effectiveness of PrEP is sensitive to the initial HIV prevalence rate, PrEP and antiretroviral therapy (ART) adherence and initiation rates, the probabilities of HIV transmission, and the rates of sexual partner mixing. CONCLUSIONS: PrEP and test-and-treat offer cost-effective alternatives to the status quo. The success of these strategies depends on ART and PrEP adherence and initiation rates. The lack of evidence on adherence behaviors toward PrEP, therefore, warrants further studies.