Genotype testing for all HIV patients, study suggests
Genotype testing for all HIV patients, study suggests
Resistance is 18 percent overall.
A recent study suggests the need for clinicians to provide genotype testing on all new HIV patients. Different geographical locations may have different patterns of resistance, so it's important for clinicians to know which types of resistance are most common in their region and to obtain genotype tests looking for those resistance patterns, says Jessica R. Grubb, MD, an instructor of medicine at Washington University in St. Louis, MO.
Grubb was a co-investigator of a study that found a high prevalence of primary resistance in an antiretroviral-naïve clinic population, between 2003 and 2005. The study included 82 women and 110 men of whom 67 percent were African American, 28 percent Caucasian, and 4 percent Latino.1 Reported transmission factors were 37 percent men who have sex with men (MSM), 59 percent heterosexual sex, and 4 percent injection drug use (IDU).1 The overall prevalence of resistance was 18 percent.1
Although there are no clear and consistent guidelines regarding resistance testing, the Midwestern clinic where the study was completed typically provides genotypes to treatment-naïve patients, Grubb says. "In the last couple of years, most of our patients have received genotypes," Grubb says. "We have a clinic population with primary care of HIV patients, and we've gotten genotypes for some years on our naïve patients."
Grubb says the study reinforces other recent data on genotyping. "I think more people in the field are getting genotypes on treatment-naïve patients," she notes. "This study reinforces what others have found in terms of rates of primary resistance, and while there is a range of resistance, it reflects the Midwest university clinic's range."
Typically, the clinic will wait for genotype testing results before initiating antiretroviral treatment, Grubb says. "At our clinic we usually obtain a genotype at the first visit and then see the patient back before making a decision about treatment," she adds. "The genotype adds to the whole picture." For example, if a patient has a K103 mutation, then clinicians would not start them on a Sustiva-based regimen, Grubb says. "So many people are started on Sustiva these days, it's good to know if they're going to be resistant to it," she adds. "We had 7 percent of our subjects with a K103 mutation."
The key is to explain the genotype test in simple terms to patients. For instance, a physician could say, "Because of changes in the HIV virus certain medications won't work well, or they'll be less effective even if the medication is great for others," Grubb suggests.
Also, if clinicians have a patient who already has established resistance, it's important to reinforce the importance of compliance because they may already have a reduced response to some medications, Grubb notes. "They may have limited options before they start their treatment," she says.
At Grubb's clinic, patients meet for an hour with a nurse practitioner who gives them HIV education. The nurse practitioner also discusses compliance issues.
Reference:
- Grubb J, et al. Patterns of primary antiretroviral resistance in antiretroviral-naïve HIV-1 infected individuals. Presented at the Infectious Diseases Society of America's 44th Annual Meeting, held Oct. 12-15, 2006, in Toronto, Ontario. Abstract: 977.
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