July 22, 2015
Written by Project Inform
This post originally appeared on the Project Inform website.
Two studies presented at the 8th International AIDS Society in Vancouver Canada (July 19 to 23) offer critical insights about PrEP and cisgender heterosexual women. One found very high rates of adherence and no infections among women taking daily PrEP in an open label fashion, while the other measured adherence and acceptance of three dosing strategies, of which a qualitative analysis suggests that common education and adherence programs may actually worsen suspicion about PrEP and lower adherence.
In the first study, an open label continuation of the Centers for Disease Control and Prevention (CDC) funded TDF2 trial, the CDC’s Faith Henderson presented an analysis of adherence among 229 heterosexual cisgender men and women who rolled over from the larger TDF2 efficacy trial (where half were randomized to receive Truvada and half did not). Individuals in TDF2 were asked if they would like to receive 48 weeks of Truvada and be followed regularly. Those who agreed, 229 in all, were tested regularly for HIV and had their adherence measured by both self report and blood level testing for the presence of tenofovir.
Forty-five percent of the participants were female and roughly 70% were single. When looking at self-reported adherence, roughly 90% reported having good or excellent adherence and this held up through the course of the study. Blood level testing in 120 of the 229 revealed that self-reported adherence was highly correlated with having detectable tenofovir in blood. While this is encouraging, and women were validated to have very high adherence, female sex was associated with slightly lower adherence levels.
Overall, the number of sex partners decreased by 12% and the number of condomless sex acts decreased by 39% during the course of the study.
There were no HIV transmissions, though statistics from the earlier TDF2 efficacy trial would have predicted 5 or 6, backing up the finding that Truvada can work well in HIV-negative women.
HPTN 067 (ADAPT)
HPTN 067 is not an efficacy study. Rather, it is designed to measure the coverage of sex acts, acceptability and adherence involved in three Truvada dosing strategies: daily, time-driven (two doses per week not driven by sex) and event-driven, where one dose is taking within 24 hours before sex and another dose 2 hours after.
There are three separate branches of ADAPT, two in men who have sex with men (MSM) and transgender women in either Harlem or Bangkok, and one in heterosexual cisgender women in South Africa. This article focuses on the study in South Africa.