OBJECTIVES: This study evaluates the budgetary impact of adding ibalizumab, a recently approved, long-acting post-attachment HIV-1 inhibitor to a United States (US) Medicare health plan for the treatment of multidrug-resistant (MDR) HIV-1 infection.

METHODS: A budget-impact model with an underlying Markov structure was developed to estimate the economic impact of including ibalizumab on a hypothetical Medicare plan with 1 million members. The model compares antiretroviral drug costs and HIV management costs over a 3-year period for two scenarios: with and without ibalizumab included on the formulary as an add-on to optimized background therapy. Model inputs were based on ibalizumab clinical trial data, market uptake projections (5%, 10%, 15%), and published literature, with costs in 2019 US dollars. The model estimates the number of treatment-eligible beneficiaries with MDR HIV-1 infection, total annual and per-member per-month (PMPM) costs for each scenario, and the incremental budget impact. Key input parameters were tested in scenario analyses.

RESULTS: In year 1, approximately 62.6 Medicare beneficiaries with MDR HIV-1 are expected to be treated with antiretroviral therapy. Adding ibalizumab to the formulary is expected to result in an annual budget impact of $252,561 ($0.021 PMPM) in year 1, $447,839 ($0.037 PMPM) in year 2, and $651,349 ($0.054 PMPM) in year 3. Scenario analyses indicated that results are most sensitive to ibalizumab uptake projections, although results are also affected by alternate assumptions related to treatment failure and ibalizumab discontinuation rates.

CONCLUSIONS: Including ibalizumab on a US Medicare health plan is expected to result in a relatively low budget impact that remains low over a 3-year time period and across a range of scenario analyses. Because Medicare beneficiaries with MDR HIV-1 infection have limited treatment options remaining, including ibalizumab on formulary may help to improve health outcomes without increasing costs substantially.