Reduced STI screening may be feasible for most PrEP users, Dutch study finds

A relatively small proportion of pre-exposure prophylaxis (PrEP)-using men who have sex with men (MSM) and transgender women accounts for most sexually transmitted infections (STIs) within that group, a modeling study conducted in the Netherlands found. Less frequent STI screening for most asymptomatic PrEP users may reduce cost and overuse of antibiotics, the authors suggested.

About This Study

“Bacterial sexually transmitted infections are concentrated in subpopulations of MSM using HIV PrEP: an analysis of longitudinal trajectories” was published online on July 28, 2023, in AIDS. The lead author is Vita W. Jongen, Ph.D., of the Department of Infectious Diseases at Public Health Service Amsterdam and of Stichting HIV Monitoring in Amsterdam, the Netherlands. The study drugs were provided by their manufacturer, Gilead Sciences.

Key Research Findings

This modeling study evaluated STI trajectories among people on PrEP based on data from 366 men who have sex with men (MSM) and transgender people who were followed for a median of 3.7 years in the Netherlands. Participants took daily or event-driven PrEP and were tested every three months for chlamydia, gonorrhea, and syphilis.

Per three-month interval, 52% of participants had about 0.1 STIs (“low overall”), 43% of participants had around 0.4 STIs (“medium overall”), and 5% of participants had between 0.3 and 1 STI (“high and fluctuating”). Most STIs were among participants in the medium and high groups (64% and 23% of all STIs, respectively).

Participants in the low group tended to be older and report less chemsex or condomless anal sex with casual partners than those in the other two groups. In the high group, STI frequency peaked around 18 months of follow-up and declined thereafter.

Discussion Highlights and Implications for Practice

Study limitations reported included participants’ characteristics (white, educated, early PrEP adopters at substantial risk of HIV acquisition), missed study visits, and participants dropping out before the end of follow-up.

The researchers speculated that the longer-term decline in STI frequency in the high group may be due to these participants starting to use condoms after treatment of several STIs.

The researchers concluded that given the concentration of STIs among relatively few participants, screening most PrEP users for STIs every six rather than three months may be feasible and such an approach would lower costs. In addition, less frequent screening may reduce the development of antibiotic resistance as a result of medication overuse when asymptomatic STIs that may clear on their own (chlamydia and gonorrhea) are treated early, the authors commented.

By Barbara Jungwirth