Clinical Newswire February 17, 2010 (San Francisco, California USA)-
Antiretroviral therapy (ART) is associated with substantially lower risk of HIV transmission among heterosexual African, HIV serodiscordant couples, according to a presentation at the 17th Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco, California from 16-19 February 2010.*
Observational studies indicate that ART is associated with decreased risk of HIV transmission, likely through reduced plasma and genital HIV levels. This prospective study enrolled 3,408 HIV discordant heterosexual couples from seven African countries. At the time of enrollment, all of the HIV-infected partners had CD4 counts >250 cells/mm2. None of the HIV-infected partners were receiving ART and none met national criteria for ART initiation.
The enrolled couples were followed for 1 to 2 years. They were given free condoms and counseled on HIV prevention. The HIV-infected partners had CD4 counts every 6 months and were referred to initiate ART when they met national guidelines or for prevention of mother-to-child transmission. The HIV unaffected partners were tested for HIV every 3 months. Time dependent analysis was used to assess the effect of ART initiation on HIV transmission risk. “A major strength of our study is that we were able to identify whether the HIV transmissions actually occurred within the couple by doing HIV sequencing analysis of the seroconverting partner and the infected partner,” said lead author Dr. Deborah Donnell of the Fred Hutchinson Cancer Research Center, Seattle, Washington USA.
During the study, 349 (10%) HIV-infected partners initiated ART. ART was initiated at CD4 counts <200 cells/mm2 in 52%, at CD4 counts of 200 to 349 cells/mm2 in 33%, and at ≧350 cells/mm2 in 15% of HIV-infected partners. A total of 103 linked HIV infections occurred during the study, with 102 of these occurring when the HIV-infected partner was not receiving ART. Only 1 linked infection occurred when the HIV-infected partner was receiving ART. “This translates to an HIV seroincidence rate of 2.2% (95% CI 1.84-2.70) for HIV-infected partners who were not on ART and 0.4% (95% CI 0.09-2.18) for those who were on ART, which was highly statistically significant,” said Dr. Donnell.
HIV transmissions occurred across all CD4 levels. The highest transmission rates were in those with CD4 counts <200 cells/mm2, with a seroincidence rate of 8.9% per year. In participants with CD4 counts >200 cells/mm2, the seroincidence rate per year was 2%. In this cohort, one-half of the linked transmissions occurred when CD4 counts were >350 cells/mm2.
“It is very clear from our data that in addition to the know treatment benefit of starting ART when CD4 counts fall below 200, there also is a substantial prevention benefit to the sexual partners. Our data also suggest that ART provides an HIV transmission benefit at CD4 counts above 200,” Dr. Donnell concluded.
*Donnell D, et al. ART and Risk of Heterosexual HIV-1 Transmission in HIV-1 Serodiscordant African Couples: A Multinational Prospective Study. CROI 2010. Symposium Session 35, Abstract 136
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