OBJECTIVES: HIV and STI prevention efforts often operate independently of each other and cost-effectiveness studies of HIV/STI testing interventions often consider only the health outcomes of one disease. We use cost-benefit analysis to evaluate 12 different HIV/STI testing interventions using only HIV health benefits (A); only STI health benefits; and both health benefits (C).
METHODS: We used a previously published stochastic agent-based network simulation model of HIV, gonorrhea, and chlamydia transmission among young men who have sex with men (YMSM) in Chicago to evaluate over 15 years the cost-benefit of 12 different HIV/STI testing interventions targeting YMSM. Among these are interventions scaling up either HIV testing or STI testing as well as opt-out interventions offering an HIV or STI test in case when requesting an STI or HIV test. Costs, in 2015 dollars, included treatment and testing cost for both HIV and STIs. The health outcomes considered were quality adjusted life years (QALY) of HIV, STIs, or HIV and STIs. We value a QALY at $50,000 (or $100,000).
RESULTS: For scenario A, increasing HIV testing by 10% (intervention 1) yielded the highest cost-benefit; for scenarios B and C the opt-out policy where automatically a test is done for urethral and rectal infections when receiving a test for HIV (intervention 2) had the highest cost-benefit. The ranking is the same for both QALY values. However, the optimal policy for scenario A is only 7th best when considering both HIV and STI health outcomes. Considering both HIV and STI health outcomes, the respective cost-benefits for interventions 1 and 2 are $17,234 ($34,497) and $20,983 ($42,025) per person per year (for $100,000/QALY in parentheses).
CONCLUSIONS: The optimal choice HIV/STI testing strategy changes if one considers both HIV and STI health outcomes and considering ignoring HIV or STI health outcomes will suggest strategies that are significantly worse.