(802) Cost Effectiveness Analysis of Outpatient Versus Inpatient Antibiotic Treatment for Syphilis in Pregnancy

Inadequate treatment and inequitable access to care contribute to the rising incidence of congenital syphilis in the US. In pregnancy, inpatient treatment is offered due to increased risk of Jarisch-Herxheimer reaction (JHR) and other adverse outcomes. Our objective is to determine the cost-effectiveness of admissions averted by comparing inpatient versus outpatient treatment for initial antibiotic dose in pregnant patients with syphilis.


Study Design:

We performed a cost effectiveness analysis using a decision tree, for viable (≥23 weeks), pregnancies with syphilis, to compare initial treatment in two settings: (1) inpatient and (2) outpatient. Input parameters included the probability of JHR resulting in a 3-day admission to the hospital among outpatient treatment, the total cost of treatment in each setting, and the total cost of subsequent admissions. Costs were estimated using a cost-to-charge ratio obtained from charges at a US, tertiary, academic hospital in 2024 USD, while the probability of admission was equated to the JHR incidence obtained from the literature (1.72%). An incremental cost-effectiveness ratio (ICER) was calculated using the ratio of differential total costs and admission probabilities between the two settings from a healthcare system perspective. A probabilistic sensitivity analysis using 100 Monte Carlo simulations was conducted to assess parameter uncertainty.


Results:

The average treatment cost of pregnant women with syphilis was estimated at $2,720 and $170 in an inpatient and outpatient setting respectively, while the cost of a 3-day admission following JHR in the outpatient settings was around $9,000. The ICER was estimated at $134,463 (95% Confidence Interval: $121,874-$149,052) per admission averted.


Conclusion:

Initial antibiotic treatment in an outpatient setting for syphilis in pregnancy is cost-effective compared to patient treatment in terms of admissions averted. Future work should explore whether the costs of treating women with syphilis in an inpatient setting are justified by exploring birth-related health outcomes (e.g. still-births averted).