August 31, 2011
Although more detailed results have since been presented (see earlier report from IAS Rome conference earlier in this issue), the following summary information was reported as a press release from the U.S. NIAID.
Initiation of Antiretroviral Treatment Protects Uninfected Sexual Partners from HIV Infection (HPTN Study 052): 96% reduction in HIV transmission, according to study conducted by HIV Prevention Trials Network
Men and women infected with HIV reduced the risk of transmitting the virus to their sexual partners through initiation of oral antiretroviral therapy (ART), according to findings from a large multinational clinical study conducted by the HIV Prevention Trials Network (HPTN), a global partnership dedicated to reducing the transmission of HIV through cutting-edge biomedical, behavioral, and structural interventions.
HPTN 052 began in April 2005 and enrolled 1,763 HIV-serodiscordant couples (couples that have one member who is HIV-infected and the other who is HIV-uninfected), the vast majority of which (97 percent) were heterosexual. The study was conducted at 13 sites across Africa, Asia and the Americas. The HIV-infected person was required to have a CD4 cell count between 350-550 per cubic millimeter (cells/mm3) at enrollment, and therefore did not require HIV treatment for his or her own health. Couples were randomized to one of two groups. In one group, the HIV-infected person immediately began taking ART (immediate ART group). In the other group, the HIV-infected person began ART when his or her CD4 cell count fell below 250 cells/mm3 or if he/she developed an AIDS-related illness (the delayed ART group).
Throughout the study, both groups received HIV-related care that included counseling on safe sex practices, free condoms, treatment for sexually transmitted infections, regular HIV testing, and frequent evaluation and treatment for any complications related to HIV infection. Each group received the same amount of care and counseling. Any HIV-uninfected person who became HIV-infected during the course of the study was referred to local services for appropriate medical care and treatment.
In its review, the DSMB found a total of 39 cases of HIV infection among the previously uninfected partners. Of those, 28 were linked through genetic analysis to the HIV-infected partner as the source of infection. Seven infections were not linked to the HIV-infected partner, and four infections are still undergoing analysis. Of the 28 linked infections, 27 infections occurred among the 877 couples in which the HIV-infected partner did not begin antiretroviral therapy immediately. Only one case of HIV infection occurred among those couples where the HIV-infected partner began immediate antiretroviral therapy. This finding was statistically significant and means that earlier initiation of antiretrovirals led to a 96 percent reduction in HIV transmission to the HIV-uninfected partner. The infections were confirmed by genetic analysis of viruses from both partners.
Additionally, 17 cases of extrapulmonary tuberculosis occurred in the HIV-infected partners in the deferred treatment arm compared with three cases in the immediate treatment arm, a statistically significant difference. There were also 23 deaths during the study. Ten occurred in the immediate treatment group and 13 in the deferred treatment group, a difference that did not reach statistical significance.
The press release noted that the ongoing international clinical study called Strategic Timing of Antiretroviral Therapy (START) also funded by NIAID is examining the optimal time for asymptomatic HIV-infected individuals to begin antiretrovirals.
Source: NIAID Press release. (12 May 2011)
For additional information about the HPTN 052 study, see the Questions and Answers information on the NIAID website.
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