ATLANTA — Treatment adherence to tenofovir-based pre-exposure prophylaxis in both pill and vaginal gel form was low among young women living in sub-Saharan Africa with a high incidence of HIV infection, according to results from the VOICE trial presented here at the 2013 Conference on Retroviruses and Opportunistic Infections. Neither treatment significantly reduced risk for infection.
“Although tenofovir has proven to be a very effective [pre-exposure prophylaxis] agent in other randomized clinical trials, we were unable to demonstrate that it worked in this highly vulnerable group of young women at high risk for HIV infection in sub-Saharan Africa, very likely due to low rates of adherence, to not just the oral products but also to the vaginal gel,” study researcher Jeanne Marrazzo, MD, MPH, professor of medicine at the University of Washington, told Infectious Disease News.
Marrazzo and colleagues conducted a five arm, randomized, double blind, placebo-controlled trial to assess the efficacy of daily use of oral tenofovir (TDF), an oral combination of tenofovir/emtricitabine (TDF/FTC) and 1% vaginal tenofovir gel (TFV) in 5,029 women (mean age, 25.3 years) who were screened at 15 sites across South Africa, Uganda and Zimbabwe. Participants were tested for HIV every month, and plasma TFV levels were assessed quarterly.
HIV incidence was 5.7 per 100 person-years, ranging from 0.8 to 9.9 per 100 person-years by site. TDF effectiveness was –48.8% (HR=1.49; 95% CI, 0.97-2.29), –4.2% (HR=1.04; 95% CI, 0.73-1.49) for TDF/FTC and 14.7% (HR=0.85; 95% CI, 0.6-1.2) for TFV gel. Among a case-cohort subset, TFV was detected on average in 28% of quarterly plasma samples among participants randomly assigned to TDF, 29% to TDF/FTC and 22% to TFV gel. Being married, being aged 25 years or younger and reporting a primary male partner aged 28 years or older were predictors of treatment adherence.
Marrazzo and colleagues identified no safety concerns, and results were consistent with those of the FEM-PrEP trial.
Marrazzo said there could be a number of reasons for the low treatment adherence among this population, with stigma being one of them.
“There is still a great deal of stigma around HIV medication, not surprisingly,” Marrazzo said during a press conference. “And that pertains to whether you are HIV infected or not HIV infected. I think concerns about what it meant to take an HIV drug are really profound for women, in partnerships, in their communities and in their families.”
For more information:
Marrazzo J. #26LB. Presented at: 20th Conference on Retroviruses and Opportunistic Infections; March 3-6, 2013; Atlanta.
Jeanne Marrazzo, MD, MPH can be reached at firstname.lastname@example.org.
Disclosure: Marrazzo reports no relevant financial disclosures.