Preexposure prophylaxis for HIV infection among African women

Abstract

Background: Preexposure prophylaxis with antiretroviral drugs has been effective in the prevention of human immunodeficiency virus (HIV) infection in some trials but not in others.

Methods: In this randomized, double-blind, placebo-controlled trial, we assigned 2120 HIV-negative women in Kenya, South Africa, and Tanzania to receive either a combination of tenofovir disoproxil fumarate and emtricitabine (TDF-FTC) or placebo once daily. The primary objective was to assess the effectiveness of TDF-FTC in preventing HIV acquisition and to evaluate safety.

Results: HIV infections occurred in 33 women in the TDF-FTC group (incidence rate, 4.7 per 100 person-years) and in 35 in the placebo group (incidence rate, 5.0 per 100 person-years), for an estimated hazard ratio in the TDF-FTC group of 0.94 (95% confidence interval, 0.59 to 1.52; P=0.81). The proportions of women with nausea, vomiting, or elevated alanine aminotransferase levels were significantly higher in the TDF-FTC group (P=0.04, P<0.001, and P=0.03, respectively). Rates of drug discontinuation because of hepatic or renal abnormalities were higher in the TDF-FTC group (4.7%) than in the placebo group (3.0%, P=0.051). Less than 40% of the HIV-uninfected women in the TDF-FTC group had evidence of recent pill use at visits that were matched to the HIV-infection window for women with seroconversion. The study was stopped early, on April 18, 2011, because of lack of efficacy.

Conclusions: Prophylaxis with TDF-FTC did not significantly reduce the rate of HIV infection and was associated with increased rates of side effects, as compared with placebo. Despite substantial counseling efforts, drug adherence appeared to be low. (Supported by the U.S. Agency for International Development and others; FEM-PrEP ClinicalTrials.gov number, NCT00625404.).

Figure 1. Screening, Randomization, and Follow-up of the Study Participants

The percentages of participants who completed the study and were included in the primary analysis were calculated on the basis of the total numbers of participants in the two randomized study groups. HIV infection at the time of enrollment was further determined by subsequent polymerase-chain-reaction assay.

Figure 2. Kaplan–Meier Estimates of the Cumulative Probability of HIV Infection

Shown are the numbers of participants who were at risk at the start of each 4-week interval. The estimated cumulative probability of HIV infection at 12 months was 0.049 in the TDF–FTC group and 0.046 in the placebo group.