Quantifying the number of people who would benefit from HIV pre-exposure prophylaxis (PrEP) in the United States: a comparison of behavioral, acquisition-risk based, and economic metrics.

Purpose: We developed metrics to estimate the number of people who could benefit from PrEP using clinical, behavioral, and economic considerations. Methods: We estimated the distribution of annual HIV acquisition risk in the U.S. population and the number who would benefit from PrEP based on HIV acquisition risk thresholds. Estimates were generated for men who have sex with men (MSM), men who have sex with women (MSW), women who have sex with men (WSM), and people who inject drugs (PWID). Populations were stratified by state, age, and race and ethnicity. Adult PWID were stratified by state and sex. We also derived a measure anchored on a willingness-to-pay threshold to gain one quality-adjusted life year (QALY). Results: We estimated 31-57% of MSM could benefit from PrEP by HIV acquisition risk thresholds, and 30% when using the cost-per-QALY threshold. For PWID, estimates ranged from 7% (cost-per-QALY) to 60% (highest risk threshold). MSW and WSM had the lowest proportions estimated to benefit (0-11%), but the absolute number of individuals remained large due to the size of these populations. Discussion: These estimates provide a broader framework in which to examine need for PrEP at the population and program level in the United States.