Syphilis Diagnosis after a Chlamydia, Gonorrhea, or HIV Diagnosis among Reproductive-Aged Women in Baltimore, MD

Background Syphilis incidence is increasing among reproductive-aged women, and previous sexually transmitted infections (STIs) are a risk factor for subsequent STIs. This study aimed to determine syphilis incidence after a chlamydia, gonorrhea, or HIV diagnosis, and identify characteristics associated with higher syphilis incidence rates among reproductive-aged women in 1 mid-Atlantic city. Methods A retrospective cohort of 85,113 chlamydia, gonorrhea, and HIV diagnoses occurring between 2009 and 2021 and among women aged 13 to 50 years was constructed using public health surveillance data. Cumulative incidence curves were estimated to examine time to early syphilis (i.e., primary, secondary, or early latent) diagnosis, and multivariable analyses determined incidence rate ratios by age (<25 vs. ≥25 years) and number of prior STI diagnoses (0 vs. ≥1) during the study period, stratified by STI. Results There were 85,113 reportable STI diagnoses and 646 syphilis diagnoses in the cohort. Approximately 1 of 150 chlamydia, 1 of 100 gonorrhea, and 1 of 50 HIV diagnoses were followed by a syphilis diagnosis within 5 years. Cumulative incidence of syphilis differed significantly by STI diagnosis (P < 0.001). In multivariable analysis, syphilis incidence rates were higher among women diagnosed with ≥1 (vs. 0) prior STI regardless of STI type (P < 0.05) and among women ≥25 (vs. <25) years old diagnosed with gonorrhea (P < 0.05). Conclusions There were significant differences in syphilis incidence by prior STI type, number of STIs, and age. Our data support targeted screening for syphilis among women with a history of STIs, parwomen with ≥1 prior STI diagnosis, and older women diagnosed with gonorrhea.