Regular sexually transmitted infection (STI) screening for people on PrEP encourages prompt diagnosis and treatment and reduces future transmission to partners. Currently, the Centers for Disease Control and Prevention recommends STI testing at least once every six months for people on PrEP. But could more frequent testing be beneficial?
Some PrEP clinics, such as the one at the San Francisco AIDS Foundation health and wellness center Strut, test PrEP clients every three months for STIs since they need to be seen every three months anyway for HIV testing and to get their PrEP prescriptions renewed. The CDC’s 2015 STD Treatment Guidelines recommend screening for men who have sex with men every three to six months, especially for those with a past history of STIs.
At this year’s Conference on Retroviruses and Opportunistic Infections (CROI), Sarit Golub, PhD, from Hunter College presented results from a study conducted to figure out the benefit of providing STI screening more often than once every six months.
The study was done with participants in the SPARK PrEP demonstration project at Callen-Lorde Community Health Center in New York City. Participants received chlamydia, gonorrhea, and syphilis tests every three months. Golub’s team analyzed data for 280 participants for the six months prior to starting and the first year on PrEP.
They found that 21% of SPARK PrEP clients had an STI during the six-month pre-PrEP period. At the three-month follow-up visit after starting PrEP, 13% were diagnosed with STIs. Three-quarters of these did not have symptoms and two-thirds did not have a prior STI history that would have triggered screening if it were not done routinely. At each follow-up visit, between 11% and 21% were diagnosed with STIs, again mostly thanks to routine screening.
Over the entire year 43% were diagnosed with at least one STI and the number with repeat diagnoses rose. Overall, STI screening according to current CDC guidelines would have delayed diagnosis and treatment for about a quarter of PrEP clients, missing 40 cases of rectal infections and three cases of syphilis.
“Current CDC guidelines may miss a significant number of asymptomatic STIs among PrEP users,” the researchers concluded, suggesting that STI screening may be warranted at each three-monthly visit, especially for those with a past STI history.
Similarly, Albert Liu, MD, from the San Francisco Department of Public Health found that quarterly screening increased the number of STI cases that were detected and treated among participants in the PrEP Demonstration Project.
Liu reported that the PrEP Demonstration Project found that about 40% of chlamydia cases, 30% of gonorrhea cases, and 20% of syphilis cases caught during quarterly screening would have been missed with bi-annual screening, extending the potential transmission period by three months. They calculated that screening every three months prevented three sex partners on average from being exposed for each STI case detected.
“Folks who are deciding to take PrEP need it—if there is an increase in STIs, it is outweighed by HIV protection,” Golub stressed at a CROI press conference. Given that PrEP is starting to roll out widely, she said, “we need to change these guidelines now, because it is much harder to tell providers to change their practices once they’ve started.”