Resistance testing of individuals recently diagnosed with HIV before the initiation of HAART would identify a substantial number of patients with mutations causing resistance to HIV drugs, according to a US study published in the June 15th edition of The Journal of Infectious Diseases. The investigators also established that gay men, whites and patients whose partners were taking HAART, were the groups of recently diagnosed patients most likely to have drug-resistant mutations prior to initiating treatment with anti-HIV drugs.
US investigators recruited 1082 patients recently diagnosed with HIV from 39 separate HIV treatment centres in ten US cities between 1997 and 2001. The investigators wished to establish the prevalence of drug resistant mutations in individuals recently infected with HIV and the characteristics of these patients.
Individuals had genotypic resistance tests performed, and plasma samples with major genotypic mutations were also tested phenotypically. All individuals were also tested using a modified HIV testing assay to see if their infection had occurred in the previous four-to-six months.
Of the 1082 patients included in the study, 90 (8.3%) had a resistance-conferring genotypic mutation. The investigators found that the prevalence of resistance varied according to HIV risk group, with 4.7% of heterosexual men having a major resistance mutation, 6.1% of women, and 12% of gay men (p=0.001). The prevalence of drug resistance also differed according to race, with 5.4% of African Americans having a resistance-conferring mutations, 7.9% of Hispanic patients, and 12% of white patients p=0.002).
Partners on HAART risk factor for acquiring drug resistance
The use of anti-HIV drugs by individuals’ partners was also found to be a risk factor for the presence of a major genotypic resistance mutation. A total of 14% of patients whose partners were taking anti-HIV medication had a resistance mutation compared to 6% of patients who did not have a partner taking antiretrovirals (p
The prevalence of genotypic resistance was higher in the 182 patients infected with HIV within the previous four-to-six months (12% versus 7.4%, p=0.07), although this difference was not statistically significant. Amongst these recently-infected patients there was a trend for gay men to be more likely to have a major genotypic resistance mutation (15% versus 11% for all other risk groups).
Successful phenotypic resistance tests were performed on 79 patients, and of these 31 (39%) showed evidence of decreased susceptibility to the drugs with which their mutations were associated.
”The findings of the present study of drug-naïve persons with newly diagnosed infections suggest that…a strategy of resistance testing would identify a substantial number of persons with HIV containing mutations associated with reduced antiretroviral-drug susceptibility”, comment the investigators.
They also emphasise that the prevalence of resistance mutations varied according to the “particular population being tested…the prevalence of mutations associated with reduced drug susceptibility was higher in whites and [men who have sex with men] than other populations. We also found that the prevalence of these mutations was higher in persons reporting partners who took antiretroviral medications”, suggesting to the investigators the sexual transmission of drug resistant HIV.
Further information on this website
Testing for resistance - overview
Resistance tests - factsheet
Resistance - booklet in the award winning information for HIV-positive people series (pdf)
Weinstock HS et al. The epidemiology of antiretroviral drug resistance among drug-naïve HIV-1-infected persons in 10 US cities. Journal of Infectious Diseases 189: 2174-2181, 2004.