COST-EFFECTIVENESS OF HIV PREEXPOSURE PROPHYLAXIS FOR INJECTION DRUG USERS IN THE UNITED STATES: A MODEL FOR OTHER COUNTRIES TOO?
Method(s): We developed a risk-stratified dynamic compartmental HIV model adaptable to a range of geographic settings and calibrated to the US epidemic. The model follows adults categorized as those who inject drugs, men who have sex with men, or individuals at low risk of HIV infection from either injection or sexual transmission routes. The model projects HIV prevalence and incidence over 20 years, both under the status quo and with PrEP. We evaluated the benefits, risks, costs, and incremental cost per quality-adjusted life year (QALY) gained from PrEP for IDUs and other risk groups not targeted by the intervention. We adopted a societal perspective, employed a lifetime horizon, and discounted both benefits and costs at 3% annually. Consistent with trial data, our base case analysis assumed a 49% reduction in infection with PrEP, which we varied in sensitivity analysis to address heterogeneity in adherence and efficacy. We also performed multiple one-way and probabilistic sensitivity analyses.
Result(s): The model predicts that PrEP for 50% of uninfected IDUs in the US would avert 66,000 HIV infections over 20 years and reduce HIV prevalence among IDUs by 36% compared to the status quo. Achieving these benefits costs $214,000 per QALY gained. At current prices, total expenditures for PrEP could be as high as $88 billion. Total costs of the intervention are highly dependent on PrEP drug price, drug efficacy, and transmission risks. PrEP is most valuable when combined with frequent HIV screening and access to treatment should an individual become infected.
Conclusion(s): PrEP for US IDUs can provide substantial health benefits but, at current drug prices, remains an expensive intervention both in absolute terms and in cost per QALY gained. In regions outside the US, PrEP could be cost-effective for high-risk IDUs if favorable pricing could be secured.