The High Risk of an HIV Diagnosis Following a Diagnosis of Syphilis: A Population-level Analysis of New York City Men

BACKGROUND: Epidemiologic studies have shown that syphilis is associated with risk for human immunodeficiency virus (HIV) infection. We used population-level syphilis and HIV data to quantify HIV incidence among men following primary or secondary (P&S) syphilis diagnoses and identify the highest-risk subgroups for intensified prevention, such as pre-exposure prophylaxis with antiretroviral medications. METHODS: Male cases reported to the New York City HIV/AIDS and Sexually Transmitted Disease (STD) surveillance registries were matched using a deterministic algorithm. We measured HIV incidence following P&S syphilis diagnosed between 2000 and June 2010 and identified risk factors for HIV infection using Cox proportional hazards models. RESULTS: Of 2805 men with syphilis contributing 11 714 person-years of follow-up, 423 (15.1%) acquired HIV; annual incidence was 3.61% (95% confidence interval [CI], 3.27%, 3.97%). HIV incidence was high among: men who have sex with men (MSM) (5.56%, 95% CI, 5.02%-6.13%); males with secondary compared with primary syphilis (4.10% vs 2.64%, P < .0001); and males diagnosed with another bacterial STD after syphilis (7.89%, 95% CI, 6.62%-9.24%). CONCLUSIONS: HIV incidence among men diagnosed with syphilis is high; one in 20 MSM were diagnosed with HIV within a year. Our data have implications for syphilis and HIV screening and may be useful for further targeting HIV-negative populations for pre-exposure prophylaxis.