Prevalence and Incidence of Syphilis After Menopause in the United States: A Retrospective Cohort Analysis Using TriNetX [ID 1434]

INTRODUCTION: Rates of syphilis have increased since 2018 despite a steady decline in other sexually transmitted infections (STIs). Postmenopausal women are an understudied population at risk for severe outcomes because of age-related changes in the vaginal microenvironment and low estrogen. There is also an increased risk of STIs because they do not need condoms for contraception. This study investigates rates and outcomes of syphilis in U.S. postmenopausal women and evaluates the effect of social determinants of health. METHODS: Deidentified TriNetX data was used to form a control cohort of all postmenopausal women, and a study cohort limited to females with ICD-10 and Logical Observation Identifier Names and Codes (LOINC) of syphilis diagnosed after the onset of menopause. Human immunodeficiency virus- and other STI-positive patients were excluded. The prevalence and incidence were determined between 2004 and 2024. Data was stratified by age, race, and ethnicity. RESULTS: The total number of postmenopausal women was 2,629,061, with 3,659 developing syphilis after menopause, giving an overall prevalence of 0.14% from 2004 to 2024. Incidence rates of syphilis increased by over 500% between 2004–2014 (0.0081%) and 2014–2024 (0.044%). Out of the total population that developed syphilis after menopause (n=3,659), 39% had late syphilis and 30% developed neurosyphilis. CONCLUSIONS/IMPLICATIONS: The overall prevalence and incidence of syphilis after menopause has increased. It is vital to investigate comorbidities associated with syphilis in this population, increase education on safe-sex practices, and encourage sexual health screening and primary care visits to prevent the onset of late syphilis and its related sequelae.