HIV pre-exposure prophylaxis, sexually transmitted infections testing intensity and antibiotic prescribing among men who have sex with men: a retrospective cohort study.

OBJECTIVES

To quantify the joint associations of time-varying HIV pre-exposure prophylaxis (PrEP) exposure and bacterial sexually transmitted infections (STIs) testing intensity on detected Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) incidence, and STI-related antibiotic prescribing among men who have sex with men.

METHODS

We conducted a retrospective cohort study using electronic health records from Maccabi Health Care Services, Israel, from January 2019 to June 2024. Men aged ≥21 years with ≥1 rectal CT/NG-PCR test were followed in 3-month intervals. PrEP exposure was classified as never, current, recent, or stopped use and lagged by one interval. Testing intensity was defined as the quarterly number of STI testing events. Outcomes were positive PCR results and outpatient prescriptions for doxycycline, azithromycin and ceftriaxone; cephalexin served as a negative control. Adjusted incidence rate ratios (aIRRs) were estimated using mixed-effects negative binomial models including a PrEP-by-testing interaction.

RESULTS

Overall, 6943 men contributed 174 516 person-months; 12 573 person-months (7.2%) included ≥1 positive CT/NG-PCR result. At annual testing intensity, current PrEP use was associated with higher detected NG and CT incidence than never use (NG aIRR 4.2; 95% CI, 3.8-5.3; CT aIRR 5.2; 95% CI, 4.0-6.6). These relative differences attenuated with increasing testing intensity. Doxycycline, azithromycin and ceftriaxone prescribing followed similar patterns, whereas cephalexin showed no consistent association with PrEP status or testing intensity.

CONCLUSIONS

In PrEP care, testing intensity was strongly associated with detected CT/NG incidence and STI-directed antibiotic prescribing. Risk-stratified testing strategies should be evaluated as part of antimicrobial stewardship in PrEP programmes.