Cost-effectiveness of the once-daily efavirenz/emtricitabine/tenofovir tablet compared with the once-daily elvitegravir/cobicistat/emtricitabine/tenofovir tablet as first-line antiretroviral therapy in HIV-infected adults in the US

BACKGROUND: February 2013 US treatment guidelines recommend the once-daily tablet of efavirenz/emtricitabine/tenofovir (Atripla®) as a preferred regimen and the once-daily tablet of elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild™) as an alternative regimen for first-line treatment of human immunodeficiency virus (HIV). This study assessed the clinical and economic trade-offs involved in using Atripla compared with Stribild as first-line antiretroviral therapy in HIV-infected US adults. METHODS: A Markov cohort model was developed to project lifetime health-related outcomes, costs, quality-adjusted life years (QALYs), and cost-effectiveness of Stribild compared with Atripla as first-line antiretroviral therapy in HIV-1-infected US patients. Patients progressed in 12-week cycles through second-line, third-line, and nonsuppressive therapies, acquired immune deficiency syndrome, and death. Baseline characteristics and first-line virologic suppression, change in CD4 count, and adverse effects (lipid, central nervous system, rash, renal) were based on 48-week clinical trial results. These results demonstrated equivalent virologic suppression between the two regimens. Point estimates for virologic suppression (favoring Stribild) were used in the base case, and equivalency was used in the scenario analysis. Published sources and expert opinion were used to estimate costs, utilities, risk of acquired immune deficiency syndrome, mortality, subsequent-line CD4 count, clinical efficacy, and adverse events. Costs were reported in 2012 US dollars. Sensitivity analyses were conducted to assess robustness of results. RESULTS: Compared with patients initiating Atripla, patients initiating Stribild were estimated to have higher lifetime costs. Stribild added 0.041 QALYs over a lifetime at an additional cost of $6,886, producing an incremental cost-effectiveness ratio of $166,287/QALY gained. Results were most sensitive to first-line response rates, product costs, and likelihood of renal adverse events. When equivalent efficacy was assumed, Atripla dominated Stribild with lower costs and greater QALYs. CONCLUSION: At a societal willingness to pay of $100,000/QALY, Stribild was not cost-effective in the base case compared with Atripla for first-line HIV treatment.