Factors associated with syphilis seroprevalence in women with and at-risk for HIV infection in the Women's Interagency HIV Study (1994-2015)

Objective Syphilis rates among women in the USA more than doubled between 2014 and 2018. We sought to identify correlates of syphilis among women enrolled in the Women's Interagency HIV Study (WIHS) to inform targeted interventions. Methods The retrospective cross-sectional analysis of secondary data included women with HIV or at-risk of HIV who enrolled in the multisite US WIHS cohort between 1994 and 2015. Syphilis screening was performed at baseline. Infection was defined serologically by a positive rapid plasma reagin test with confirmatory treponemal antibodies. Sociodemographic and behavioural characteristics stratified by baseline syphilis status were compared for women enrolled during early (1994-2002) and recent (2011-2015) years. Multivariable binomial modelling with backward selection (p>0.2 for removal) was used to model correlates of syphilis. Results The study included 3692 women in the early cohort and 1182 women in the recent cohort. Syphilis prevalence at enrolment was 7.5% and 3.7% in each cohort, respectively (p<0.01). In adjusted models for the early cohort, factors associated with syphilis included age, black race, low income, hepatitis C seropositivity, drug use, HIV infection and >100 lifetime sex partners (all p<0.05). In the recent cohort, age (adjusted prevalence OR (aPOR) 0.2, 95% CI 0.1 to 0.6 for 30-39 years; aPOR 0.5, 95% CI 0.2 to 1.0 for 40-49 years vs ≥50 years), hepatitis C seropositivity (aPOR 2.1, 95% CI 1.0 to 4.1) and problem alcohol use (aPOR 2.2, 95% CI 1.1 to 4.4) were associated with infection. Conclusions Syphilis screening is critical for women with HIV and at-risk of HIV. Targeted prevention efforts should focus on women with hepatitis C and problem alcohol use.