Cost-effectiveness of tenofovir/emtricitabine compared with other NRTI pairs in treatment-naïve adults with HIV infection in the USA

Abstract

Methods Lifetime costs and health outcomes for a treatment-naive cohort were modeled using a Markov framework with six health states based on CD4 cell-count ranges. Efficacy data for first-line therapy were based on 144-week results of Study 934 comparing TDF/FTC + efavirenz [EFV] with ZDV/3TC + EFV and normalized 48-week results of Study CNA30024 comparing ABC/3TC + EFV with ZDV/3TC + EFV. Immune response data were used to calculate transition probabilities between the CD4-based health states. Individuals with viral loads higher than 400 copies/mL switched to second-line therapy at rates estimated over time using exponential functions fitted to trial data. Costs and efficacy for subsequent therapy lines were based on likely baskets of second-line, third-line, and non-suppressive therapy regimens. Costs for antiretroviral drugs were based on 2008 wholesale acquisition costs. Utility values, mortality rates, and costs for other medical resources were obtained from published sources. Adverse events observed in Studies 934 and CNA30024 were accounted for in modeled costs and outcomes. Base-case results were tested in one-way and probabilistic sensitivity analyses (PSA).