Third-trimester prenatal syphilis screening

OBJECTIVE: To estimate the cost to prevent one case of congenital syphilis or fetal or neonatal death with universal third-trimester syphilis rescreening in the United States and to estimate the incidence of syphilis seroconversion at which rescreening becomes cost-effective. METHODS: We created a decision model comparing universal third-trimester syphilis rescreening in women who screened negative in the first trimester with no rescreening. The assumed base case incidence of seroconversion was 0.012%. The primary outcome was the cost to prevent one case of congenital syphilis. Secondary outcomes included the cost to prevent one fetal or neonatal death and the number needed to rescreen to prevent one adverse outcome. A strategy was considered cost-effective if it cost less than $285,000 to prevent one case of congenital syphilis (the estimated long-term care cost). RESULTS: Under our assumptions, universal third-trimester rescreening would cost an additional $419,842 for each case of congenital syphilis prevented and $3,621,144 and $6,052,534, respectively, for each fetal and neonatal death prevented. Rescreening 4,000,000 women would prevent 60 cases of congenital syphilis and seven fetal and four neonatal deaths. Prevention of one case of congenital syphilis would require 65,790 women be rescreened. Seroconversion incidence of 0.017% would make third-trimester rescreening cost-effective. CONCLUSION: Universal third-trimester syphilis rescreening requires a large number of women be rescreened at a high health care cost to prevent one adverse outcome from maternal syphilis. Seroconversion incidence must be 19-fold higher than the national average of primary and secondary syphilis in women for universal third-trimester rescreening to be cost-effective.