Background: Daily oral antiretroviral preexposure prophylaxis (PrEP) is a promising strategy for prevention of HIV-1 acquisition. Three clinical trials demonstrated PrEP efficacy; however, two PrEP trials among women did not find protection against HIV-1. One hypothesis proposed for these divergent results is that PrEP efficacy may be reduced in populations with higher HIV-1 incidence.
Methods: Using data from the Partners PrEP Study, a randomized, placebo-controlled trial of daily oral tenofovir (TDF) and emtricitabine/tenofovir (FTC/TDF) PrEP among heterosexual HIV-1 serodiscordant couples from Kenya and Uganda, we assessed PrEP efficacy among subgroups at higher risk for HIV-1 acquisition, including subgroups of women with high HIV-1 incidence.
Results: The overall placebo arm HIV-1 incidence was 2.0 per 100 person-years. Among higher risk subgroups, placebo arm HIV-1 incidence ranged from 3.9 to 6.6 per 100 person-years. In all subgroups, PrEP was protective against HIV-1 acquisition, with efficacy point estimates ranging from 64 to 84%. Among subgroups of women with placebo-arm HIV-1 incidence more than 5.0, efficacy estimates ranged from 64 to 84%. Monthly visit attendance for PrEP refills and tenofovir detection in plasma were high.
Conclusion: Among higher-risk subgroups in the Partners PrEP Study, including groups solely of higher-risk women, both TDF alone and combined FTC/TDF PrEP had consistently high efficacy for HIV-1 protection. PrEP, when used with high adherence, is a highly effective prevention strategy for higher risk heterosexuals. Prioritizing PrEP for persons at high risk of HIV-1 will maximize its prevention impact.
aDepartment of Epidemiology
bDepartment of Global Health
cDepartment of Medicine, University of Washington, Seattle, Washington, USA
dDepartment of Obstetrics and Gynaecology, University of Nairobi
eDepartment of Obstetrics & Gynaecology, Kenyatta National Hospital, Nairobi, Kenya
fDivision of HIV/AIDS Prevention, National Center for HIV, Viral Hepatitis, STD and TB Prevention, CDC-Uganda, Entebbe, Uganda
gDivision of Infectious Diseases and Tropical Pediatrics, Department of Pediatrics, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland
hStatistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
iCenters for Disease Control and Prevention, Atlanta, Georgia, USA.
*Members of the Partners PrEP Study Team listed at end of paper.
Correspondence to Jared Baeten, University of Washington, 325 Ninth Avenue, UW Box 359927, Seattle, WA 98104, USA. Tel: +1 206 520 3808; fax: +1 206 520 3831; e-mail: firstname.lastname@example.org
Received 1 February, 2013
Revised 15 April, 2013
Accepted 24 April, 2013