Cost-effectiveness of adding an agent that improves immune responses to initial antiretroviral therapy (ART) in HIV-infected patients: guidance for drug development.

PURPOSE: Adding an immune-enhancing agent to initial antiretroviral therapy (ART) for HIV is a potential strategy to ensure that patients achieve optimal immune response.
METHOD: Using a mathematical model of HIV disease and treatment, we evaluated the treatment benefits and cost-effectiveness of adding a hypothetical immune-enhancing agent to the initial 6 months of ART. We assumed that the additional agent would result in a higher CD4 increase that would provide clinical benefit. The additional cost ($1,900/month) was based on the cost of a drug currently under investigation for immune enhancement. Outcomes included projected life expectancy and cost-effectiveness in 2009 US dollars/quality-adjusted life year (QALY) with costs and QALYs discounted at 3% annually.
RESULTS: Compared to standard ART, immune-enhanced ART resulting in an additional 40 CD4 cell/µL increase at 6 months yields a 2.4 month projected undiscounted life expectancy increase with a cost-effectiveness ratio of $107,600/QALY. Achieving a cost-effectiveness ratio <$100,000/QALY requires a >43 CD4 cell/µL improvement, or >19 cells/µL if immune-enhancing agent costs are halved.
CONCLUSIONS: In addition to showing clinical efficacy, investigational immune enhancement agents need to increase CD4 counts more than has been previously observed or have a lower cost to be considered cost-effective in the United States.