Cost-Effectiveness of HIV Preexposure Prophylaxis for People Who Inject Drugs in the United States

Abstract

Background: The total population health benefits and costs of HIV preexposure prophylaxis (PrEP) for people who inject drugs (PWID) in the United States are unclear.

Objective: To evaluate the cost-effectiveness and optimal delivery conditions of PrEP for PWID.

Design: Empirically calibrated dynamic compartmental model.

Data sources: Published literature and expert opinion.

Target population: Adult U.S. PWID.

Time horizon: 20 years and lifetime.

Intervention: PrEP alone, PrEP with frequent screening (PrEP+screen), and PrEP+screen with enhanced provision of antiretroviral therapy (ART) for individuals who become infected (PrEP+screen+ART). All scenarios are considered at 25% coverage.

Outcome measures: Infections averted, deaths averted, change in HIV prevalence, discounted costs (in 2015 U.S. dollars), discounted quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios.

Results of base-case analysis: PrEP+screen+ART dominates other strategies, averting 26 700 infections and reducing HIV prevalence among PWID by 14% compared with the status quo. Achieving these benefits costs $253 000 per QALY gained. At current drug prices, total expenditures for PrEP+screen+ART could be as high as $44 billion over 20 years.

Results of sensitivity analysis: Cost-effectiveness of the intervention is linear in the annual cost of PrEP and is dependent on PrEP drug adherence, individual transmission risks, and community HIV prevalence.

Limitation: Data on risk stratification and achievable PrEP efficacy levels for U.S. PWID are limited.

Conclusion: PrEP with frequent screening and prompt treatment for those who become infected can reduce HIV burden among PWID and provide health benefits for the entire U.S. population, but, at current drug prices, it remains an expensive intervention both in absolute terms and in cost per QALY gained.

Primary funding source: National Institute on Drug Abuse.

Figure 1. Main analysis: incremental costs incurred and QALYs gained

To assess delivery scenarios, we evaluated 1) PrEP alone with status quo population-level screening rates for people who inject drugs; 2) PrEP with HIV screening every 3 mo (PrEP+screen); and 3) PrEP+screen with prompt and sustained linkage to ART for individuals who do become infected (PrEP+screen+ART). All cases assume 25% coverage, 49% PrEP efficacy, and $10 000 annual PrEP drug cost. The x-axis shows incremental cost in billions of U.S. dollars compared with the status quo of no PrEP; the y-axis shows incremental QALYs in thousands. The point labeled PrEP+screen shows that at current levels of ART initiation and adherence, screening provides a small QALY increase for a large cost increase. When screening is combined with increased ART, however, screening delivers synergistic benefit, resulting in an ICER of $253 000/QALY gained. This scenario, PrEP+screen+ART, dominates the other 2 scenarios (i.e., is more effective and has a lower ICER). ART = antiretroviral therapy; ICER = incremental cost-effectiveness ratio; PrEP = preexposure prophylaxis; QALY = quality-adjusted life-year.

Figure 2. Sensitivity analysis: PrEP value as a function of drug efficacy and drug cost

We evaluate a program of PrEP with frequent HIV screening and enhanced ART provision (PrEP+screen+ART) with 25% coverage and $10 000 annual PrEP drug cost varying PrEP efficacy from 10% to 90%. The y-axis shows the ICER corresponding to efficacy levels specified on the x-axis. At current drug costs, the cost per QALY gained remains greater than $150 000 for all efficacy levels but substantially decreases as efficacy improves, with the largest jumps in cost-effectiveness coming at lower levels of efficacy. At 49% efficacy (leftmost vertical line), we see our base-case analysis with an ICER of $253 000/QALY gained. The Bangkok Tenofovir Study estimates a 74% reduction (rightmost vertical line) in HIV acquisition for high adherers. This results in a more favorable ICER of $193 000/QALY gained. At a 65% cost reduction PrEP delivers higher value and crosses the $100 000/QALY gained threshold at reported efficacy levels, although low levels of efficacy still result in high ICERs. ART = antiretroviral therapy; ICER = incremental cost-effectiveness ratio; PrEP = preexposure prophylaxis; QALY = quality-adjusted life-year.