Background HIV PrEP is highly effective at preventing HIV, but not STI, acquisition. We examined the use of condoms to prevent STIs among PrEP-users in the EPIC-NSW trial.

Methods Between March 2016 and April 2018, 9,708 individuals were enrolled. Analysis was restricted to participants who completed the optional end-of-study survey and were on-study for ≥1 year prior. STI diagnoses came from medical records; other data were from the end-of-study survey. We used multivariate logistic regression to assess independent associations between those agreeing with the statement, “I use condoms to avoid getting STIs” (“STI-condom-users”) and those disagreeing.

Results 2,915 participants were included; 92.5% were gay men. In the previous year, 54.2%, 25.6%, and 20.2% were diagnosed with no, one, and ≥2 STIs, respectively. 1,127 (38.7%) reported being STI-condom-users. In multivariate analysis, there was no difference in mean STIs diagnosed in the previous year (0.7 vs 0.8, p=0.244). STI-condom-users were younger (39 vs 41 years, p=0.004), less likely to live in a suburb with ≥10% gay men (24.8% vs 35.5%, p<0.001), less likely to report any condomless sex in the previous 6 months (85.9% vs 93.3%, p<0.001), and had been on-study less time (1.4 vs 1.6 years, p=0.003). STI-condom-users were more: concerned about acquiring STIs (95.1% vs 88.9%, p=0.025), likely to discuss STI results with partners (88.3% vs 79.8%, p<0.001), and likely to believe condoms prevent STI transmission (96.7% vs 89.6%, p<0.001). Fewer STI-condom-users had rejected a sexual partner for wanting to use condoms (9.6% vs 32.7%, p<0.001), while more had been rejected for wanting to use condoms (45.0% vs 26.2%, p<0.001).

Conclusion Most PrEP-users did not use condoms for STI prevention, despite strong beliefs in its effectiveness. STI-condom-users did not have fewer STIs, reflecting high levels of condomless sex. Our results suggest alternative methods of STI prevention should be trialled for PrEP-users.

Disclosure No significant relationships.