Study finds antiretroviral-based strategies to prevent HIV infection among women prove ineffective

There was no statistically significant difference in the rate of new infections between women assigned to the three investigational products and women using placebo. Among the 994 women who were assigned to daily use of Truvada, 61 women became infected with HIV (4.7 percent rate of new infections) compared with 60 of 1,008 women who became infected in the oral placebo group (4.6 percent rate of new infections). Of the 1,002 participants in the daily oral tenofovir group, 60 women acquired HIV. However, the rate of new HIV infections was calculated to reflect what had occurred up until Oct. 3, 2011, when study sites began informing participants that testing of oral tenofovir would end. At this time, 52 women acquired HIV (6.3 percent rate of new infections) compared with 35 of 1,008 women who became infected in the placebo arm (4.2 percent rate of new infections). Of the 1,003 women assigned to use daily tenofovir gel, 61 became infected with HIV (5.9 percent rate of new infections), and 70 infections occurred among the 1,000 women in the placebo gel group (6.8 percent rate of new infections). Women who became infected with HIV during the VOICE study were referred to local sites for appropriate medical care and treatment.

During the course of the study, adherence to each of the three approaches was anticipated to be roughly 90 percent based on what study participants reported to clinic site staff and monthly counts of unused gel applicators and leftover study pills that were returned to the sites. However, in a blood sample analysis of 773 participants, including 185 participants who became HIV-infected, it became clear that adherence was low across each of the study's three investigational product groups. Drug was detected in the blood of 29 percent of the women in the Truvada group, 28 percent in the oral tenofovir group and 23 percent among those in the tenofovir gel group. When examining the data by age, young, single women were less likely to use their assigned treatment strategy. For example, among the women assigned to use oral Truvada, drug was detected in the blood of only 21 percent of young, single women compared to 54 percent of those married and over the age of 25.

"Based on our findings, it is clear that young, single women in Africa continue to be at very high risk for HIV infection and may need the greatest assistance with using prevention strategies consistently," said Dr. Marrazzo. Among VOICE study participants, the rate of new HIV infections was nearly 9 percent among unmarried women under the age of 25 compared to 0.8 percent for older married women, a statistically significant difference.

Through two ongoing behavioral studies involving VOICE participants, researchers are hoping to gain insight as to why the women did or did not use the investigational products. Results from those two studies are expected later this year.

Source: NIH/National Institute of Allergy and Infectious Diseases