Syphilis Testing and Diagnosis Among People With Human Immunodeficiency Virus (HIV) Engaged in Care at 4 US Clinical Sites, 2014-2018

Background: Despite rising rates of syphilis among people with human immunodeficiency virus (HIV; PWH) in the United States, there is no optimal syphilis screening frequency or prioritization. Methods: We reviewed records of all PWH in care between 1 January 2014 and 16 November 2018 from 4 sites in the Centers for AIDS Research Network of Integrated Clinical Systems Cohort (CNICS; N = 8455). We calculated rates of syphilis testing and incident syphilis and used Cox proportional hazards models modified for recurrent events to examine demographic and clinical predictors of testing and diagnosis. Results: Participants contributed 29 568 person-years of follow-up. The rate of syphilis testing was 118 tests per 100 person-years (95% confidence interval [CI]: 117-119). The rate of incident syphilis was 4.7 cases per 100 person-years (95% CI: 4.5-5.0). Syphilis diagnosis rates were highest among younger cisgender men who have sex with men and transgender women, Hispanic individuals, people who inject drugs, and those with detectable HIV RNA, rectal infections, and hepatitis C. Conclusions: We identified PWH who may benefit from more frequent syphilis testing and interventions for syphilis prevention.