(297) 12 Versus 24 Hours of Postpartum Magnesium Sulfate for Seizure Prophylaxis: A Cost-Effective Analysis

To assess the cost-effectiveness of using 12 hours versus 24 hours of postpartum magnesium sulfate for preeclampsia with severe features to prevent eclampsia.

Study Design:

We developed a decision-analysis model to determine the cost-effectiveness of 12 versus 24 hours of postpartum magnesium sulfate to prevent eclampsia using TreeAge software. Outcomes included maternal death, eclampsia, eclampsia within 0-12 hours postpartum, eclampsia within 12-24 hours postpartum, and magnesium toxicity in a theoretical cohort of 47,000 patients diagnosed with preeclampsia with severe features. Probability estimates for seizure, magnesium side effects, toxicity, and the cost of nursing ratios were determined from the literature. The cost-effectiveness threshold was set to $100,000/QALY.

Results:

12 hours of postpartum magnesium sulfate results in 88 more instances of eclampsia in our theoretical cohort compared to 24 hours. However, 12 hours has 169 more QALYs than 24 hours and costs $15 million less than 24 hours. Overall, this is a cost-saving strategy: -$88k/QALY. NNT: 531 people with preeclampsia with severe features treated with 24 hours of postpartum magnesium sulfate to prevent 1 instance of eclampsia.

Conclusion:

Though there are more instances of eclampsia, and 1-2 additional maternal deaths in the 12-hour group compared to the 24-hour group, the possibility of time not on magnesium sulfate, with its toxicity risk and disutility, is driving the overall relative QALY increase and cost savings of the 12-hour treatment dose. The routine use of 12 hours of postpartum magnesium sulfate should be considered for patients with preeclampsia with severe features in a shared decision-making approach.