647: The cost effectiveness of GBS screening vs. universal intrapartum antibiotic prophylaxis

Abstract

Group B streptococcus (GBS) is the leading cause of neonatal sepsis in the US. As such, rectovaginal culture for all women between 35-37 weeks gestation is recommended to screen for those colonized with the pathogen. Early onset disease in neonates can be prevented by intrapartum antibiotic prophylaxis (IAP), but missed screening opportunities and false negative maternal cultures result in preventable neonatal disease. We sought to evaluate the cost-effectiveness of universal IAP in reducing neonatal morbidity and mortality related to GBS. A decision-analytic model was created using TreeAgePro; probabilities, costs, and utilities were derived from the literature. We compared universal screening with rectovaginal culture by 37 weeks gestation to no screening and IAP given to all women at delivery after 37 weeks. This model was applied to a theoretical cohort of 1,600,000 women with no documented penicillin allergy based on the estimated number of nulliparous, term-births annually in the United States. The cost-effectiveness threshold was set to $100,000 per quality adjusted life year (QALY). Univariate sensitivity analyses were used to evaluate the robustness of the results. In our theoretical cohort of 1.6 million women, we found that IAP given to all laboring women, no matter their GBS status, was cost effective when compared to IAP given to GBS positive women based on screening culture. Universal IAP results in 803 fewer cases of neonatal sepsis, 29 fewer cases of meningitis, 13 fewer cases of neurodevelopmental delay, and 24 fewer neonatal deaths, despite an increase in cases of maternal anaphylaxis, maternal death from anaphylaxis, and increased cost overall. The universal antibiotics strategy resulted in 1,134 additional QALYs and an incremental cost effectiveness ratio of $22,300/QALY. Univariate sensitivity analysis demonstrated that universal IAP was cost-effective when the cost of culture was between $16.75 and $48.25, and was cost-saving for culture cost above $48.25. Our findings suggest that the current standard of care for prenatal screening of GBS may not be cost-effective compared to prophylactically treating all women in pregnancy with penicillin. Further research is necessary to determine if a change in diagnostic test or screening strategy would improve maternal and neonatal outcomes.