September 26, 2005
Resistance to antiretroviral therapy, even in patients who have never received treatment, is a growing concern. However, genotype resistance testing, which involves looking for the presence of resistance genes, is not a standard procedure at the time a patient is diagnosed with HIV, probably due to lack of data on its benefits and its relatively high cost compared with other routine blood tests.
A cost-effectiveness analysis conducted by a group of Boston researchers indicates that performing genotype resistance testing at initial HIV diagnosis -- before treatment is started -- can effectively guide a physician's choice of treatment regimen and increase a patient's quality-adjusted life expectancy. (Quality-adjusted measurements of time reflect that survival with an illness is presumed to be of lower quality than healthy survival.)
"For the approximately 90 percent of patients with no resistance, the testing provides no benefit," said lead author Paul Sax, M.D., of Brigham and Women's Hospital. "However, if certain types of resistance are present [when a patient is first diagnosed with HIV], our study projects a substantial increase in survival" of more than 14 months, compared with no resistance testing.
An accompanying editorial commentary by Frederick Hecht, M.D., and Robert Grant, M.D., of the University of California, San Francisco, agrees that "there is now sufficiently strong information to recommend genotypic resistance testing in all drug naive patients at the time of diagnosis." However, the authors, who have received support from various pharmaceutical and diagnostic companies, caution that there are some drug resistance mutations that may not be detectable by standard resistance tests.
The cost of performing the one-time test -- now about $400 -- has decreased from when it was first approved, and will likely continue to drop. Some physicians are not yet convinced of the value of genotype resistance testing, and some insurance companies do not yet cover it, but the practice of resistance testing at initial HIV diagnosis has gradually increased. "We're hoping that this study makes it part of standard care," said Dr. Sax.