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Review
. 2018 Aug;34(8):645-656.
doi: 10.1089/AID.2018.0031. Epub 2018 Jun 19.

Weighing the Evidence of Efficacy of Oral PrEP for HIV Prevention in Women in Southern Africa

Holly Janes  1   2 , Lawrence Corey  1   3   4 , Gita Ramjee  5   6   7 , Lindsay N Carpp  1 , Carl Lombard  8 , Myron S Cohen  9 , Peter B Gilbert  1   2 , Glenda E Gray  10   11
Affiliations
Review

Weighing the Evidence of Efficacy of Oral PrEP for HIV Prevention in Women in Southern Africa

Holly Janes et al. AIDS Res Hum Retroviruses. 2018 Aug.

Abstract

As oral tenofovir-based regimens for preexposure prophylaxis (PrEP) are adopted as standard of care for HIV prevention, their utilization in clinical trials among women in southern Africa will require an accurate estimate of oral PrEP efficacy in this population. This information is critical for women in choosing this prevention strategy, and in public health policy making. Estimates of the efficacy of oral PrEP regimens containing tenofovir have varied widely across trials that enrolled women, with some studies reporting high efficacy and others reporting no efficacy. Although poor adherence is strongly associated with lack of efficacy, other factors, such as mode of transmission (sexual vs. parenteral), predominant HIV subtype (C vs. non-C), intensity of exposure, and percentage of stable serodiscordant couples, may also contribute to the variation in efficacy estimates. In this article, we evaluate the evidence for PrEP efficacy in women and propose potential explanations for the observed differences in efficacy among studies. Our review emphasizes the need to continue to refine estimates of efficacy and effectiveness of tenofovir-based oral PrEP so as to best develop the next generation of HIV prevention tools, and to inform public policies directed toward HIV prevention.

Keywords: HIV prevention; adherence; oral PrEP efficacy; preexposure prophylaxis; southern African women.

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Conflict of interest statement

Dr. Cohen is on the Advisory Board for both Merck and Gilead, and has served on Merck and Gilead advisory boards. The other authors declare no conflicts of interest.

Figures

<b>FIG. 1.</b>
FIG. 1.
Characteristics of the populations of women enrolled in PrEP efficacy trials with sexual HIV transmission. Varying adherence is the leading explanation for different efficacy results across trials, but the role of adherence cannot be studied in isolation: adherence is confounded with circulating HIV subtypes, placebo group incidence, and whether HIV serodiscordant partners or individual women at risk were recruited. For each trial the estimated PrEP versus placebo HR is reported. Details on the adherence and HIV subtype data are included in Appendix 1. HR, hazard ratio; PrEP, preexposure prophylaxis.
<b>FIG. 2.</b>
FIG. 2.
Correlation between PrEP efficacy estimates in women and placebo group HIV incidence (A) and adherence based on plasma drug detection (B) in women, for PrEP efficacy trials with sexual HIV transmission. Details on the adherence data are included in Appendix 1.
See this image and copyright information in PMC

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Appendix References

    1. Van Damme L, Corneli A, Ahmed K, et al. : Preexposure prophylaxis for HIV infection among African women. N Engl J Med 2012;367:411–22 - PMC - PubMed
    1. Thigpen MC, Kebaabetswe PM, Paxton LA, et al. : Antiretroviral preexposure prophylaxis for heterosexual HIV transmission in Botswana. N Engl J Med 2012;367:423–34 - PubMed
    1. Marrazzo JM, Ramjee G, Richardson BA, et al. : Tenofovir-based preexposure prophylaxis for HIV infection among African women. N Engl J Med 2015;372:509–18 - PMC - PubMed
    1. Baeten JM, Donnell D, Ndase P, et al. : Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N Engl J Med 2012;367:399–410 - PMC - PubMed

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