(1215) Prophylactic antibiotics for women with PROM >18 hours: A cost effectiveness analysis

Objective:
Prelabor rupture of membranes (PROM) increases the risk of chorioamnionitis and worsens perinatal outcomes. For PROM >18 hours, this risk is even higher. Historically, such patients received antibiotic prophylaxis, but this has declined in the GBS screening era. A recent study re-examined prophylaxis in this population. We evaluated the cost-effectiveness of giving antibiotics (ampicillin-gentamicin) vs. expectant management in patients who were GBS negative with PROM >18 hours.

Study Design:
We built a decision-analytic model in TreeAge Pro comparing prophylactic ampicillin-gentamicin to expectant management. The theoretical cohort included 255,000 U.S. patients with term singleton pregnancies, negative GBS, and prolonged PROM. Outcomes included chorioamnionitis, postpartum endometritis, uterine atony, blood transfusion, neonatal early-onset sepsis (nEOS), neonatal death, neonatal neurodevelopmental delay (nNDD), maternal acute kidney injury (AKI) from gentamicin, costs, and quality-adjusted life years (QALYs). The willingness-to-pay threshold was $100,000/QALY. QALYs were discounted at 3%. Inputs were literature-based and tested with univariate sensitivity analyses.

Results:
In our cohort of 255,000 individuals, ampicillin-gentamicin prophylaxis led to fewer cases of chorioamnionitis (2,550 vs. 22,950), endometritis (4,514 vs. 4,932), uterine atony (14,747 vs. 16,407), blood transfusion (5,164 vs. 5,651), nEOS (61 vs. 135), neonatal deaths (1,436 vs. 1,443), and nNDD (17,725 vs. 17,728) compared to expectant management. However, gentamicin use resulted in 56 more maternal AKI cases. This reduction in adverse outcomes with prophylactic antibiotics led to lower costs, making it a dominant, cost-effective strategy. Sensitivity analyses showed antibiotics remained cost-effective as long as there is a 12% reduction in chorioamnionitis risk in the prophylaxis group vs the expectant management group.

Conclusion:
Treating PROM >18 hours with ampicillin-gentamicin reduced chorioamnionitis and improved outcomes, making it a cost-effective strategy. This approach warrants reconsideration in clinical practice.