Study: PrEP demonstrates effectiveness, but alongside growing STI rate

SAN FRANCISCO — The findings from a study published in this month’s issue of Clinical Infectious Diseases tout the effectiveness of HIV pre-exposure prophylaxis (PrEP), marketed as Truvada (tenofovir/embtricitabine). According to the study — completed with information from patients at the Kaiser Permanente San Francisco Medical Center — though the rates of sexually transmitted diseases have gone up among PrEP users, the population examined saw no new HIV infections. 

The study looked at 657 individuals beginning PrEP at the medical center (99% of whom were men who have sex with men). After six months, 30% were diagnosed with any STI,  a number that grew to 50% after 12 months. However, when looking at 388 person-years of follow-up (meaning the cumulative time all participants were taking PrEP), nthere were no diagnoses of HIV. This is also despite the fact that 41% of 143 users had decreased condom use after 6 months.

According to the study’s authors, in a group with similarly high rate of STIs, they would expect and 8.9 out of 100 person-years incidence of HIV without PrEP use. And though the study has the limitations — the authors cite lack of a control group, higher rates of HIV incidence and viral undetectability in San Franciso and the lack of information on the HIV status of the participants’ partners, the results point to PrEP’s promise even in high-risk populations.

Additionally, in a commentary on the study, Kimberly Koester of the University of California, San Francisco, and Robert Grant of UCSF, Gladstone Institutes and the San Franciso AIDS Foundation, noted that the study demonstrates the ability for PrEP treatment to be integrated into primary care visits — something they say isn’t always the case among MSM, who may get PrEP at community clinics or elsewhere.

“It is time for a vigorous conversation about sexually transmitted infections, too long eclipsed by fear of HIV infection. The conversation should include public health officers, clinicians, clients and sexual partners,” Koester and Grant wrote. “Idally the public health response to the possibility of rising incidence of STIs int eh context of decreased or no new HIV infections would be framed in relative terms and therefore considered to be a good problem to have.”