(818) Missed Opportunities: RPR Positivity at Delivery, Evaluating Perinatal Outcomes by Syphilis Treatment Adequacy

The congenital syphilis rate in the United States has risen eight times within the last decade. We compared characteristics and perinatal outcomes among patients with a positive rapid plasma reagin (RPR) test at delivery by adequacy of syphilis treatment.

Study Design:
We conducted a retrospective cohort study of all patients with a positive RPR at delivery at a tertiary care center (Dec 2019–Dec 2023). Deliveries were classified as adequately treated (completed stage-appropriate penicillin during this pregnancy without reinfection) or inadequately treated. False-positives and serofast results from infections treated previously were excluded from analysis. Data were abstracted from medical records. Primary outcomes were preterm birth and NICU admission; secondary outcomes included birthweight, neonatal death, infant RPR positivity, and infant treatment. Chi-square, Fisher’s exact, and Wilcoxon rank-sum tests were used. Multivariable logistic regression was performed for adjusted analyses.

Results:
Among 14,405 deliveries, 162 had a positive RPR, with 109 meeting inclusion criteria. Of these, 76 (70%) were adequately treated; 63 (83%) were newly diagnosed during pregnancy and 13 (17%) were diagnosed prior to pregnancy and treated during prenatal care. Of 33 inadequately treated cases, 26 (79%) were diagnosed during pregnancy, including 18 (55%) newly identified at delivery. Inadequately treated patients were more likely to be older (31 vs 26 years, p< 0.001), have limited prenatal care (58% vs 4%, p< 0.001), comorbid Hepatitis C (36% vs 8%, p=0.001), and illicit substance use (82% vs 38%, p< 0.001). Preterm birth rates did not differ by cohort, but NICU admissions were higher in inadequately treated cases (aOR 14.1, 95% CI 2.5-266.1). Inadequately treated cases also had lower birthweight (p< 0.001) and were more likely to require 10 days of neonatal treatment (p< 0.001).

Conclusion:
Most inadequately treated syphilis cases at delivery were diagnoses made at time of delivery. Inadequate treatment is strongly associated with social vulnerability and adverse neonatal outcomes.