Sexually Transmitted Infections Among Men Who Have Sex With Men Using Daily and Event-Driven HIV Pre-Exposure Prophylaxis: A Retrospective Cohort Study.
- 1Melbourne Sexual Health Centre, Bayside Health, Melbourne, Victoria, Australia.
- 2School of Translational Medicine, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia.
- 3Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia.
Abstract
Background
HIV pre-exposure prophylaxis (PrEP) has reduced HIV incidence among men who have sex with men (MSM), but bacterial sexually transmitted infections (STIs) remain common, with limited data comparing regimens.Methods
A retrospective cohort study was conducted at Melbourne Sexual Health Centre, Australia (2024-2025). MSM aged ≥18 reporting PrEP use (daily, event-driven, or switching) who were tested for chlamydia, gonorrhea, or syphilis were included. Positivity was assessed at first consultation (baseline); incidence was assessed among those with ≥2 tests ≥30 days apart. Logistic and Poisson regression estimated associations and incidence rate ratios.Results
Among 3229 PrEP users (median age 33, IQR 29-39), 51.0% were daily, 43.2% event-driven, and 5.8% switchers. At baseline, 33.7% (765/2268) had any STI, with lower positivity among event-driven users (29.8%) than daily users (37.0%) or switchers (37.6%; P = .001), primarily driven by differences in gonorrhea positivity. After adjustment, event-driven PrEP use was independently associated with lower odds of baseline STI positivity (aOR 0.75, 95% CI 0.62-0.90), while Medicare ineligibility and recent partners had higher odds. Over 700.6 person-years, any-STI incidence (39.4/100 person-years) did not differ across regimens.Conclusions
Although event-driven users had lower baseline STI positivity, incidence was similar across regimens, suggesting baseline differences reflect underlying risk profiles rather than ongoing risk.
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BibTeX
@article{wijekoon2026sexually,
title = {{Sexually Transmitted Infections Among Men Who Have Sex With Men Using Daily and Event-Driven HIV Pre-Exposure Prophylaxis: A Retrospective Cohort Study.}},
author = {Danushi Wijekoon and Ei T Aung and Phyu Mon Latt and Andrew Buchanan and Nyi Nyi Soe and Eric P F Chow},
journal = {Open forum infectious diseases},
year = {2026},
month = oct,
doi = {10.1093/ofid/ofag643},
url = {https://europepmc.org/article/MED/42909880},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Sexually Transmitted Infections Among Men Who Have Sex With Men Using Daily and Event-Driven HIV Pre-Exposure Prophylaxis: A Retrospective Cohort Study.
AU - Danushi Wijekoon
AU - Ei T Aung
AU - Phyu Mon Latt
AU - Andrew Buchanan
AU - Nyi Nyi Soe
AU - Eric P F Chow
PY - 2026
DA - 2026/10/05
JO - Open forum infectious diseases
DO - 10.1093/ofid/ofag643
UR - https://europepmc.org/article/MED/42909880
AB - Background HIV pre-exposure prophylaxis (PrEP) has reduced HIV incidence among men who have sex with men (MSM), but bacterial sexually transmitted infections (STIs) remain common, with limited data comparing regimens.Methods A retrospective cohort study was conducted at Melbourne Sexual Health Centre, Australia (2024-2025). MSM aged ≥18 reporting PrEP use (daily, event-driven, or switching) who were tested for chlamydia, gonorrhea, or syphilis were included. Positivity was assessed at first consultation (baseline); incidence was assessed among those with ≥2 tests ≥30 days apart. Logistic and Poisson regression estimated associations and incidence rate ratios.Results Among 3229 PrEP users (median age 33, IQR 29-39), 51.0% were daily, 43.2% event-driven, and 5.8% switchers. At baseline, 33.7% (765/2268) had any STI, with lower positivity among event-driven users (29.8%) than daily users (37.0%) or switchers (37.6%; P = .001), primarily driven by differences in gonorrhea positivity. After adjustment, event-driven PrEP use was independently associated with lower odds of baseline STI positivity (aOR 0.75, 95% CI 0.62-0.90), while Medicare ineligibility and recent partners had higher odds. Over 700.6 person-years, any-STI incidence (39.4/100 person-years) did not differ across regimens.Conclusions Although event-driven users had lower baseline STI positivity, incidence was similar across regimens, suggesting baseline differences reflect underlying risk profiles rather than ongoing risk.
SN - 2328-8957
ER -