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Improved adherence to PrEP led to less HIV transmission
High adherence to pre-exposure prophylaxis, or PrEP, resulted in reduced HIV transmission to uninfected partners in serodiscordant couples in East Africa, researchers reported in PLOS Medicine.
“Previous studies of PrEP have found considerable variance in efficacy, ranging from as high as 75% to no effect at all,” Jessica Haberer, MD, MS, of the Center for Global Health at Massachusetts General Hospital, said in a press release. “We think that the different levels of adherence in those trials explain the differences in their findings, a hypothesis that is supported by this new study.”
Haberer and colleagues evaluated data from the Partners PrEP Study, a trial that tested the benefit of PrEP with tenofovir (Viread, Gilead) and emtricitabine/tenofovir (Truvada, Gilead) for the HIV-uninfected partners of a serodiscordant couple. For this study, the researchers measured PrEP adherence using unannounced home-based pill counts and electronic pill bottle monitoring.
Among the participants included in the adherence study, there were 14 HIV infections among the 1,147 uninfected participants, all of which were in those who received placebo. During 807 person-years, the median adherence was 99.1% according to data from unannounced pill counts and 97.2% according to electronic pill bottle monitoring.
Factors associated with less than 80% adherence included reports of no sex, sex with a person besides the study partner, younger age and heavy alcohol use. Polygamous marriage and the first 6 months of PrEP use were associated with more than 80% adherence.
“PrEP is another important biomedical tool for the prevention of HIV infection in sub-Saharan Africa or anywhere in the world where people are at high risk for acquiring the virus,” Haberer said. “No one tool will work for all people in all settings, so it’s important to have options.”
Disclosure: The researchers report no relevant financial disclosures.