ASM Microbe

ASM Microbe

June 23, 2016
4 min read

PrEP initiation gains mostly seen in males, whites

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BOSTON — While there was a more than 500% increase in the use of pre-exposure prophylaxis, or PrEP, for HIV prevention in the United States between 2013 and 2015, initiation has been slow among blacks, Hispanics, women and young people, according to data presented here.

“In each race, the growth has been in males,” Staci Bush, PA-C, associate director of medical affairs at Gilead Sciences, said during a presentation at ASM Microbe 2016. “And if you compare the races, you see the overwhelming amount of new initiators for Truvada for PrEP have been white.”

From Jan. 1, 2012, to Sept. 30, 2015, Bush and colleagues collected electronic patient-level data from 82% of U.S. retail pharmacies that dispensed Truvada (emtricitabine/tenofovir disoproxil fumarate, Gilead Sciences; FTC/TDF) for PrEP and projected the data to account for all retail pharmacies in the country and, to a small extent, nonretail pharmacies. They excluded patients who were using FTC/TDF for HIV treatment, post-exposure prophylaxis and off-label treatment of chronic hepatitis B virus. Data on race was available for 43.7% of the 49,148 patients who began FTC/TDF for PrEP during the study period.

Although black men and women are among the likeliest demographics to be diagnosed with HIV in their lifetime, according to recent CDC estimates, blacks represented just 10.1% of the patients who initiated PrEP during the study period, with the proportion decreasing from 12.3% in 2012 to 9.7% in 2015, Bush said. In comparison, 74% of new PrEP patients were white, 12% were Hispanic, and 4% were Asian.

Further, black women were more than four times less likely to have initiated PrEP than white women. The number of women who initiated PrEP remained the same year over year and the percentage of women overall was just 20.7%, the percent dropping from 48.5% in 2012 to 11.4% in the third quarter of 2015.

And while one in five new HIV diagnoses occurs in patients who are aged younger than 25 years, just 7.6% of those who initiated FTC/TDF for PrEP during the study period were in that age group. Among them, 73.2% were white, despite the fact that whites comprise only 17% of the new HIV infections in 2014. Blacks, who are 56% of new infections, accounted for just 11.5% of the new PrEP patients, while Hispanics, 22% of new infections, also were underrepresented at 12.2% of new PrEP starts.

“HIV prevention and education and PrEP services may need to be racially focused and culturally relevant to increase PrEP uptake and decrease new infections in the populations at the greatest risk,” Bush said.

Meta-analysis shows low seroconversion rate

According to the results of a meta-analysis presented here, HIV-1 seroconversion is rare among patients taking FTC/TDF for PrEP, with a rate below 1 out of every 100 patient-years (PY). However, seroconversion is seen disproportionately among black men who have sex with men (MSM), and more data are needed on women and transgender people, said Scott McCallister, MD, senior director of clinical research at Gilead Sciences.

McCallister and colleagues collected data from 32 individual studies in 16 countries, including 30 that began after FTC/TDF was approved for PrEP by the FDA in July 2012. Dried blood spot analysis was used to evaluate tenofovir-diphosphate levels in red blood cells and seroconversion rates and confidence intervals were computed using exact Poisson statistics. The studies included 8,478 participants representing 7,061 cumulative person-years of exposure to once-daily FTC/TDF.

In all, 67 HIV-1 seroconversions occurred — mostly among men who have sex with men — a rate of around 0.95 per 100 person-years (95% CI, 0.74-1.21). The median age of the patients who experienced seroconversion was 25.3 years. Twenty-five were black and 29 lived in the United States, tops in both categories.

Seventeen of the 32 studies, encompassing 2,467 participants and 1,315 person-years, experienced no seroconversions while just six had rates above 1.5 per 100 person-years.

Among the studies that saw no seroconversions, eight were conducted in North America, six in Africa, two in Europe and one in Australia. All six studies that observed seroconversion rates above 1.5 per 100 person-years were conducted, at least in part, in North America, with some projects including sites in Africa, Asia and South America. MSM aged 18 to 25 years had the highest seroconversion rate in the studies at 7.7 per 100 person-years.

Collectively, 64 of the 67 overall seroconversions occurred in men (n = 6,214) — all of them MSM — at a rate of 1.03 per 100 person-years (95% CI, 0.8-1.32). Two seroconversions occurred in women (n = 788) at a rate of 0.25 per person-years (95% CI, 0.03-0.92), and one occurred in transgender women (n = 76) at a rate of 2.07 per 100 person-years (95% CI, 0.05-11.52).

“I think the low seroconversion rate among women is very encouraging,” McCallister said during a presentation at ASM Microbe 2016. “The highest rate occurred in the youngest MSMs, and we have data to suggest that those MSMs were simply not taking the drug.” – by Gerard Gallagher


Bush S, et al. Racial characteristics of FTC/TDF for pre-exposure prophylaxis users in the US. Presented at: ASM Microbe; June 16-20, 2016; Boston.

McCallister S, et al. HIV-1 seroconversion across 17 international demonstration projects using pre-exposure prophylaxis (PrEP) with oral emtricitabine/tenofovir disoproxil fumarate (FTC/TDF). Presented at: ASM Microbe; June 16-20, 2016; Boston.

Disclosure: All of the researchers are employees and shareholders of Gilead Sciences.