Results of multinational trials echo some of the findings of earlier ARV-based prevention trials among women in Southern Africa
The headline of a press release announcing the results of the ASPIRE study tells a familiar enough story that, but for the numbers, the rest is easy to guess.
“Vaginal Ring Provides Partial Protection from HIV in Large Multinational Trial,” the headline says. ” . . . Study Finds Protective Effect Strongest in Women over Age 25 . . .”
The ring in question, loaded with an antiretroviral drug, showed no protection against HIV at all for women aged 18 to 21, no statistically significant protection in women younger than 25 years, and reduced the risk of HIV infection by 27 percent among the population of study participants overall. The boost comes from, as the announcement puts it, the greater risk reduction among women 25 and older “who used the ring most consistently.”
For the 2,600 women participating in the trial at sites in Malawi, South Africa, Uganda and Zimbabwe, the ring was to be inserted and remain in place for a month at a time and returned monthly. Researchers then checked the amount of antiretroviral product remaining in the ring as a measure of how much it had been used. Rings with less product remaining had been used more and researchers said that use correlated with lower rates of HIV infection.
Findings of the ASPIRE trial and the very similar findings of the concurrent Ring study were released at a press conference today, prior to the opening of CROI 2016, the Conference on Retroviruses and Opportunistic Infections in Boston, and hailed as encouraging by the researchers presenting them. They compared overall findings that the ring brought lowered risks of infection to 27 percent of the women in the ASPIRE trial and 31 percent in the Ring study with “flat findings” from previous trials which tested vaginal microbicide gels that needed to be inserted repeatedly. The vaginal rings tested in the ASPIRE and Ring trials were intended to address obstacles to repeated use which could include where to keep the product before use and applicators after in settings where privacy might be a barrier to use, as well as access to the product when it was needed. In this case however,women enrolled in the trial, 91 percent of whom kept all appointments with researchers, had to actively remove the ring to not use it.
The findings were published today in the New England Journal of Medicine, and will be presented in greater depth at a session here Wednesday.