HIV PRE-EXPOSURE PROPHYLAXIS (PREP) IN THE UNITED STATES: LIFETIME INFECTION RISK, CLINICAL OUTCOMES, AND COST-EFFECTIVENESS

Purpose: Dramatic advances in HIV treatment contrast with the persistent challenges of HIV prevention and vaccine development. Recently, the combination of tenofovir (TDF) and emtricitabine (FTC) has shown promise as a prevention intervention in healthy people at risk of infection. However, its long-term impact on transmission, clinical outcomes, and cost is unknown.

Methods: We adapted a widely published Monte Carlo simulation of HIV acquisition, detection, and care to forecast performance of PrEP in persons at high risk (mean age 20 years; average annual HIV incidence 1.6%) in the US. Base case assumptions were matched to published evidence of TDF/FTC preventive efficacy (50%), treatment costs ($8,700/year), resistance-related reductions in efficacy of subsequent HIV treatment (0-15%), toxicity-induced decrements in quality of life (0-2%), and behavioral offsets to reduced HIV transmission.

Results: PrEP reduced lifetime HIV infection risk from 55.1% to 33.4% and increased survival from 24.0 to 25.1 discounted QALYs. Discounted mean lifetime treatment costs increased from $115,300 to $262,100 per person, suggesting an incremental cost-effectiveness ratio (ICER) of $136,000 per QALY gained. Greater PrEP efficacy (90%) produced a lower lifetime infection risk (7.9%). More favorable ICERs were obtained with small improvements in the assumed cost and efficacy of PrEP and by targeting higher-incidence populations. (See figure.) Increased behavioral disinhibition yielded less favorable results. Assumptions regarding ART resistance and PrEP toxicity had little impact on outcomes.

Conclusions: PrEP could substantially reduce HIV transmission in high-risk populations. Although it is unlikely to confer sufficient benefits to justify current TDF/FTC costs, modest price reductions and/or improvements in efficacy could make PrEP a cost-effective option.