Evaluating the impact of prioritization of antiretroviral pre-exposure prophylaxis in New York City.

OBJECTIVE: To compare the value and effectiveness of different prioritization strategies of pre-exposure prophylaxis (PrEP) in New York City (NYC). DESIGN: Mathematical modelling utilized as clinical trial is not feasible. METHODS: Using a model accounting for both sexual and parenteral transmission of HIV, we compare different prioritization strategies (PPS) for PrEP with two scenarios - no PrEP and PrEP for all susceptible at-risk individuals. The PPS included PrEP for all MSM, only high-risk MSM, high-risk heterosexuals, and IDUs, and all combinations of these four strategies. Outcomes included HIV infections averted, and incremental cost-effectiveness (per-infection averted) ratios. Initial assumptions regarding PrEP included a 44% reduction in HIV transmission, 50% uptake in the prioritized population and an annual cost per person of $9762. Sensitivity analyses on key parameters were conducted. RESULTS: Prioritization to all MSM results in a 19% reduction in new HIV infections. Compared with PrEP for all persons at-risk, this PPS retains 79% of the preventive effect at 15% of the total cost. PrEP prioritized to only high-risk MSM results in a reduction in new HIV infections of 15%. This PPS retains 60% of the preventive effect at 6% of the total cost. There are diminishing returns when PrEP utilization is expanded beyond this group. CONCLUSION: PrEP implementation is relatively cost-inefficient under our initial assumptions. Our results suggest that PrEP should first be promoted among MSM who are at particularly high risk of HIV acquisition. Further expansion beyond this group may be cost-effective, but is unlikely to be cost-saving.