Antiretrovirals Protect Partners of HIV-Infected Patients
May 12, 2011 — Starting HIV-infected patients immediately after diagnosis on oral antiretroviral therapy (ART) while their immune systems are still relatively healthy is highly effective in protecting their partners from infection, according to a federally sponsored, multinational clinical trial.
ART proved so effective in blocking HIV transmission that the phase 3 clinical trial, HIV Prevention Trials Network (HPTN) Study 052, set to run until 2015, was halted so that all HIV-infected participants could begin therapy, regardless of their immune-system status, according to the National Institute of Allergy and Infectious Diseases (NIAID), which sponsored the study and released the results today.
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| Dr. Sten Vermund |
"Now we've proven that," said Dr. Vermund in an interview with Medscape Medical News.
Dr. Vermund, a professor of pediatrics at the University of Vanderbilt School of Medicine and director of the Vanderbilt Institute of Global Health, Nashville, Tennessee, said the HPTN findings provide "a powerful policy argument" to encourage widespread testing of individuals to identify those with HIV and get them started right away on ART, not only for their sake but also for their partners'.
96% Reduction in HIV Transmission With Immediate ART
The study involved 1763 serodiscordant couples. The vast majority were heterosexual and lived in 13 sites in Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, and the United States.
Most of the couples were married, noted Dr. Vermund. The sex of the infected partner was close to a 50-50 split between men and women.
At the onset of the trial, all the infected partners had CD4 cell counts that did not warrant HIV treatment for their health.
In 1 treatment group of the study, HIV-infected partners began taking a combination of 3 oral antiretroviral drugs. In the other treatment group, HIV-infected partners delayed ART until the onset of an AIDS-related illness or a decline in their CD4 count to below 250 cells/mm3, a trigger point set by the World Health Organization that the organization raised to 350 cells/mm3 in the middle of the study.
Both groups received safe-sex counseling, free condoms, frequent HIV testing, and other pertinent medical services.
Of the 877 couples that delayed ART, the researchers found 27 cases of an HIV-infected patient passing the virus to a previously uninfected partner. In contrast, only 1 case of HIV transmission occurred among the 886 couples in which ART had started immediately for the originally infected partner, which amounted to a 96% reduction in the rate of HIV transmission to the other partner, according to NIAID.
Dr. Vermund said the efficacy of ART in preventing HIV transmission should not prompt serodiscordant couples to abandon other safe-sex practices such as condom use. "But let's be honest," he said. "Most of the couples were married. They may be building families. So maybe they don't want to use a condom all the time."
Immediate ART May Have Health Benefits for HIV-Infected Patients
Beyond the issue of preventing HIV transmission, a secondary goal of the HPTN 052 study was to evaluate the optimal time to begin ART for the sake of reducing illness and death among HIV-infected individuals. The timing of ART gets debated, said Dr. Vermund, with the adverse effects and expense of the therapy prompting some to advocate waiting until a patient's immune system takes a turn toward the worse.
Study results were promising but were not conclusive when it comes to choosing immediate over delayed treatment. There were 17 cases of extrapulmonary tuberculosis among HIV-infected participants in the delayed-treatment group compared with 3 cases in the immediate-treatment group — a statistically significant difference, according to NIAID. Of the 23 deaths among study participants, 13 occurred in the delayed-treatment group compared with 10 in the other group. Some of the deaths were not related to HIV, noted Dr. Vermund.
When all morbidity and mortality events were tallied, "there was a trend towards benefit" with immediate ART, "but it did not reach the 20% difference between study arms required for statistical significance," according to an NIAID fact sheet.
More information on the trial is available at the NIAID Web site.
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