Back HIV Prevention Pre-exposure (PrEP) IAS 2015: U.S. PrEP Demo Project Finds People at Highest HIV Risk Take PrEP Most Consistently

IAS 2015: U.S. PrEP Demo Project Finds People at Highest HIV Risk Take PrEP Most Consistently


An open-label demonstration project of Truvada pre-exposure prophylaxis (PrEP) in the U.S. has found generally high retention and adherence rates, with the highest adherence among people at the highest risk of HIV infection, researchers reported at the 8th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2015) last week in Vancouver. However, some groups appeared to have more difficulty taking PrEP -- most notably young people and black people, and it proved difficult to recruit black men and transgender women -- to the project.

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The U.S. Demo Project previously released interim figures in 2014. In this study, 557 gay and bisexual men and transgender women in San Francisco, Miami, and Washington, DC, received PrEP on an open-label basis for a year.

The criteria for entry included (in the past 12 months): condomless anal sex with 2 or more partners, anal sex (with a condom or not) with 2 or more known HIV-positive partners, or diagnosis of syphilis, rectal gonorrhea, or chlamydia.

The average age of participants was 35 years, with 20% being under 25. 48% were white, 35% Latino, 7% black, and 10% mixed race or other. Just over half (54%) came forward specifically for the study, while the other 46% were referred by doctors during a check-up. Only 1.3% (7 individuals) were transgender women.

A high proportion of participants (24%) reported having a primary partner who was living with HIV (the viral load of HIV-positive partners was not specified), while 26% had a sexually transmitted infection (STI) diagnosed at baseline.

Retention in the study was good, with 78% of those originally enrolled remaining in the study at 12 months. 15% interrupted PrEP for reasons to do with side effects -- mainly nausea or headache during the first month -- but most resumed it again.

Not counting these interruptions, adherence as measured by drug levels was good, averaged over the whole study -- roughly 85% throughout. 63% of participants had protective levels of PrEP (equivalent to at least 4 doses of Truvada a week) at all levels. Only 3% of study participants had drug levels that indicated fewer than 2 doses a week at all visits.

As reported in the previous summary, however, adherence was notably lower among participants from Miami, at 65%, compared to 90% in San Francisco and 88% in Washington.

Participants in Miami tended to be younger, were more likely to be black, and had somewhat lower levels of HIV risk behavior. There was a strong relationship between ethnicity and adherence: 97% of white participants and 77% of Latinos had tenofovir levels in their blood indicating 4 or more doses a week, but only 57% of black people.

Adherence was 89% throughout among participants who had condomless sex with 2 or more sexual partners during the previous 3 months, compared with 75% for those who had less condomless sex. The only other strong predictor of adherence was that the person was in stable housing: people in unstable housing or who were homeless only took half as much PrEP.

Two-thirds of participants reported condomless receptive anal sex in the previous 3 months throughout the study, with an average of 8 episodes. However, the proportion who had receptive anal sex with a condom declined significantly during the study, from 6 episodes in the previous 3 months at the start of the study to only 2.5 by the end. Thus, although the overall number of episodes of anal sex fell, fewer episodes involved using condoms and there was therefore clear evidence of some substitution of PrEP for condoms with some partners.

The rate of rectal STIs was 17% at baseline and declined to 10% at week 24, but was back to baseline levels at week 48; this variation was not statistically significant, though. Syphilis was diagnosed in 2%-4% of participants at each visit.

A total of 3 participants turned out to have acute HIV infection and were in the testing "window period" at enrolment. They therefore started PrEP although they already had HIV, and 1 developed drug resistance to emtricitabine.

However, there were only 2 new infections among the 557 participants during the study period: 1 at 19 weeks in a participant who had stopped taking PrEP at least a month before and 1 at 4 weeks after the end of the period of PrEP allocation (participants were recalled for 1 post-study visit). The second person had drug levels indicative of taking only 2 doses a week at week 48 and none at week 52.

After the study, participants were referred to local medical providers to continue to have their PrEP provided. Researcher Bob Grant said that the number of local providers willing both to provide PrEP and to advertise that fact had increased during the study.


IAS 2015: PrEP Adherence, Sexual Behavior, and HIV and STI Incidence [VIDEO]



A Liu, S Cohen, E Vittinghoff, et al. Adherence, sexual behavior and HIV/STI incidence among men who have sex with men (MSM) and transgender women (TGW) in the US PrEP demonstration (Demo) project. 8th International AIDS Society Conference on HIV Pathogenesis, Treatment, and Prevention. Vancouver, July 19-22, 2015. AbstractTUAC0202.