Cost effectiveness of resistance testing for treatment-naive patients

In the 1st November issue of Clinical Infectious Diseases, Paul Sax and colleagues from Massachusetts General Hospital and the Harvard Medical School presented their analysis of the cost-effectiveness of resistance testing in treatment-naive patients prior to starting treatment.

They used a model of HIV disease to project life expectancy, costs, and cost-effectiveness in a hypothetical cohort of antiretroviral-naive patients with chronic HIV infection and assumed baseline prevalence of 8.3% drug resistance.

Results form the study showed that the model predicted that a strategy of genotype-resistance testing at initial diagnosis of HIV infection increased per-person quality-adjusted life expectancy by one month, with an incremental cost-effectiveness ratio of $23,900 per quality-adjusted life-year (QALY) gained, compared with no genotype testing. The cost-effectiveness ratio for resistance testing remained less than $50,000 per QALY 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.

The study concluded that genotype-resistance testing of chronically HIV-positive, antiretroviral-naive patients is likely to improve clinical outcomes and is cost-effective, compared with other HIV care in the United States and that resistance testing at the time of diagnosis should be the standard of care.

Comment

The cost-effectiveness of resistance testing prior to starting HAART has already been reported in HTB, together with the high estimated prevalence of transmitted drug resistance in the UK (10-18%).

This use of resistance testing was first recommended in BHIVA treatment guidelines in 2003, and this recommendation was strengthened in 2005.

However, results from the 2005 BHIVA national audit, presented at its conference in October, showed that over the last year only fifty percent of treatment-naive patients across the UK were given resistance testing on diagnosis or prior to starting treatment. It is a real concern that patients are losing the opportunity to identify risk of treatment failure prior to initiating treatment regimens, that are likely to be suboptimal, and more likely to lead to additional accumulated mutations.

Sax PE, Islam R, Walensky RP et al. Should resistance testing be performed for treatment-naive HIV-infected patients? A cost-effectiveness analysis. Clin Inf Dis, Volume 41 (2005) 9: 1316-1323.