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Repeated Syphilis Episodes in HIV-Infected Men Who Have Sex With Men: A Multicenter Prospective Cohort Study on Risk Factors and the Potential Role of Syphilis Immunity

Jan A Roth, Fabian C Franzeck, Suraj Balakrishna, Stephan Lautenschlager, Maria Christine Thurnheer, Laurence Toutous Trellu, Matthias Cavassini, Pietro Vernazza, Enos Bernasconi, Dominique Braun, Roger D Kouyos, Manuel Battegay & Swiss HIV Cohort Study (SHCS)

abstract

Background
Syphilis is re-emerging globally in general and HIV-infected populations, and repeated syphilis episodes may play a central role in syphilis transmission among core groups. Besides sexual behavioral factors, little is known about determinants of repeated syphilis episodes in HIV-infected individuals-including the potential impact of preceding syphilis episodes on subsequent syphilis risk.

Methods
In the prospective Swiss HIV cohort study, with routine syphilis testing since 2004, we analyzed HIV-infected men who have sex with men (MSM). Our primary outcome was first and repeated syphilis episodes. We used univariable and multivariable Andersen-Gill models to evaluate risk factors for first and repeated incident syphilis episodes.

Results
Within the 14-year observation period, we included 2513 HIV-infected MSM with an initially negative syphilis test. In the univariable and multivariable analysis, the number of prior syphilis episodes (adjusted hazard ratio [aHR] per 1-episode increase, 1.15; 95% confidence interval [CI], 1.01-1.31), having occasional sexual partners with or without condomless anal sex (aHR, 4.99; 95% CI, 4.08-6.11; and aHR, 2.54; 95% CI, 2.10-3.07), and being currently on antiretroviral therapy (aHR, 1.62; 95% CI, 1.21-2.16) were associated with incident syphilis.

Conclusions
In HIV-infected MSM, we observed no indication of decreased syphilis risk with repeated syphilis episodes. The extent of sexual risk behavior over time was the strongest risk factor for repeated syphilis episodes. The observed association of antiretroviral therapy with repeated syphilis episodes warrants further immunological and epidemiological investigation.
   
citation Roth J A, Franzeck F C, Balakrishna S, Lautenschlager S, Thurnheer M C, Trellu L T, Cavassini M, Vernazza P, Bernasconi E, Braun D, Kouyos R D, Battegay M, Swiss HIV Cohort Study (SHCS) . Repeated Syphilis Episodes in HIV-Infected Men Who Have Sex With Men: A Multicenter Prospective Cohort Study on Risk Factors and the Potential Role of Syphilis Immunity. Open Forum Infect Dis 2020; 7:ofaa019.
   
type journal paper/review (English)
date of publishing 12-01-2020
journal title Open Forum Infect Dis (7/1)
ISSN print 2328-8957
pages ofaa019
PubMed 32016128
DOI 10.1093/ofid/ofaa019