Should resistance testing be performed for treatment-naive HIV-infected patients? A cost-effectiveness analysis

Background. Data from the United States and Europe show a population prevalence of baseline drug resistance of 8%-10% among human immunodeficiency virus (HIV)-infected patients who are antiretroviral naive. Our objective was to determine the clinical impact and cost-effectiveness of genotype resistance testing for treatment-naive patients with chronic HIV infection. Methods. We utilized a state-transition model of HIV disease to project life expectancy, costs, and cost-effectiveness in a hypothetical cohort of antiretroviral-naive patients with chronic HIV infection. On the basis of a US survey of treatment-naive patients from the Centers for Disease Control and Prevention, we used a baseline prevalence of drug resistance of 8.3%. Results. A strategy of genotype-resistance testing at initial diagnosis of HIV infection increased per-person quality-adjusted life expectancy by 1.0 months, with an incremental cost-effectiveness ratio of $23,900 per quality-adjusted life-year gained, compared with no genotype testing. The cost-effectiveness ratio for resistance testing remained less than $50,000 per quality-adjusted life-year gained, unless the prevalence of resistance was <= 1%, a level lower than those reported in most regions of the United States and Europe. In sensitivity analyses, the cost-effectiveness remained favorable through wide variations in baseline assumptions, including variations in genotype cost, prevalence of resistance overall and to individual drug classes, and sensitivity of resistance testing. Conclusions. Genotype-resistance testing of chronically HIV-infected, antiretroviral-naive patients is likely to improve clinical outcomes and is cost-effective, compared with other HIV care in the United States. Resistance testing at the time of diagnosis should be the standard of care.