HIV-1 drug resistance genotyping. A review of clinical and economic issues.

The development of mutations associated with resistance to antiretroviral therapy (ART) has been shown to be a major cause of treatment failure in patients infected with HIV-1. These resistance mutations can be assessed by a genotyping test that probes for specific mutations within the HIV genome or sequences specific genes, at a cost $US500/test (2000 prices). The stated goal of HIV-1 genotyping is to target HIV therapy effectively. This, as shown in the preliminary research, should result in better clinical outcomes and a lower incidence of virological failure and may be associated with lower costs of treatment. Failure of ART may result in an increase in costs of at least $US250 per patient per month, as assessed in 1 study, with costs rising further as patients experience multiple virological failures. Therefore, there is an economic as well as a therapeutic premium on the prevention of ART failure. The actual economic cost of genotyping has been preliminarily explored in the context of the antiretroVIRal ADAPTation (VIRADAPT) trial, which found no significant difference in the 1-year treatment cost of patients with and without genotyping. There is some evidence of cost neutrality or savings with genotypic testing but it needs to be further explored within the context of carefully framed prospective trials.