High syphilis prevalence and incidence in people living with HIV and Preexposure Prophylaxis users: A retrospective review in the French Dat'AIDS cohort.

Background: In the past years, we observed a sharp increase of Syphilis, especially among male who have sex with male (MSM), either HIV-infected, or on pre-exposure prophylaxis (PrEP). Our aim was to assess syphilis prevalence and incidence among people living with HIV (PLWH) and PrEP users.
Methods: PLWH were included from 2010 to 2020 and PrEP users from 2016 to 2020 from the Dat'AIDS French cohort. We calculated syphilis prevalence and incidences for first infections, re-infections, and iterative infections (> 2 times). T-Tests, Wilcoxon tests and Chi2 test were used for descriptive analysis and multivariate logistic regression models were used to estimate Odds ratios (OR) and 95% confidence intervals (95% CI) for factors associated with syphilis.
Results: Among the 8 583 PLWH, prevalence of subject with past or present syphilis was 19.9%. These subjects were more likely MSM or transgender and aged over 35 years, but prevalence was lower in AIDS subjects. Same pattern was seen for incident infection and re-infection. Incidence was 3.8 per 100 person-years for infection and 6.5 per 100 person-years for re-infection. Among 1 680 PrEP users, syphilis prevalence was 25.8%, with an estimated 7.2% frequency of active syphilis. Risk of syphilis infection was higher in male and increased with age. Incidence was 11.2 per 100 person-years for infection and 11.1 per 100 person-years for re-infection.
Conclusion: Syphilis prevalence and incidence were high, especially in older MSM with controlled HIV infection and PrEP users, enhancing the need to improve syphilis screening and behavioral risk reduction counseling among high-risk subjects.
Competing Interests: D. Rey declared having received grants from ViiV Healthcare (expert board participation and fee for lecture) and Mylan (fee for lecture). C. Allavena declared having received grants from Gilead, Janssen, MSD, ViiV Healthcare. L. Cotte declared having received grants from Abbvie, Gilead Science, Janssen Cilag, MSD, ViiV Healthcare. For the remaining authors no other conflicts of interest were declared.