HIV-positive gay men with resistance to at least one anti-HIV drug are as likely as individuals with no drug resistance to have unprotected anal sex, and significantly more likely to have insertive unprotected anal sex with partners known to be HIV-negative, according to a poster presentation at the Eleventh Conference on Retroviruses and Opportunistic Infections in San Francisco.
Investigators from the University of California, San Francisco, wished to determine the prevalence of high-risk sexual behaviour in individuals with genotypically proven resistance to at least one anti-HIV drug and to determine the risk factors for unsafe sex.
Between autumn 2000 and spring 2003, 287 HIV-positive men and women currently taking HAART were tested for genotypic resistance to antiretrovirals. They also completed a questionnaire about their sexual activity and recreational drug use in the previous four months.
The investigators established that 27% of gay men taking HAART with drug resistance and detectable viral load had unprotected anal sex in the previous four months, compared to 31% of gay men taking HAART with no resistance. The difference was not statistically significant (p=0.50). Similar proportions of gay men also had unprotected anal sex with men of unknown HIV status or who were HIV-negative (17% versus 13%, p=0.37).
However, the investigators did find that 5% of gay men with resistance engaged in the sexual activity most likely to result in HIV transmission: unprotected anal sex with an HIV-negative partner, compared to only 1% of gay men with no resistance. This difference was statistically significant (p=0.09).
Data were also gathered for heterosexual men and women. The investigators found that 17% of individuals with resistance had unprotected vaginal or anal sex compared to 23% of individuals with no resistance (p=0.56), and that 6% of men or women had unprotected penetrative sex with a partner who was HIV-negative or of unknown HIV status, compared to 15% of individuals with no resistance (p=0.21).
The investigators then looked for risk factors predictive of an individual with resistance having unprotected penetrative sex with an HIV-negative partner. They found that age under 35 years (p<0.01), less than a college education (p=0.09), the use of the anti-impotence drug Viagra (sidenafil) (p<0.01), and depression (p=0.03), were all predictive of high-risk sexual behaviour that could involve onward HIV transmission.
Individuals with resistance having unprotected sex which carried a risk of HIV transmission had a median viral load of 10,500 copies/mL, and had had unprotected sex with a median of six partners in the previous four months, meaning that the potential number of new drug-resistant HIV-infected partners in the study period was 324.
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High-risk sexual behavior in HIV-infected adults with genotypically proven antiretroviral resistance. Eleventh Conference on Retroviruses and Opportunistic Infections, San Francisco, abstract 845, 2004