COST-EFFECTIVENESS OF ROUTINE USE OF MAGNESIUM SULFATE FOR SEIZURE PROPHYLAXIS IN MILD PREECLAMPSIA

Purpose: Preeclampsia, a hypertensive condition affecting 5-8% of pregnancies, carries a risk of seizure that can be halved by administering intravenous magnesium sulfate (MgSO₄) during labor. Guidelines recommend MgSO₄ for “severe preeclampsia”, but there is no consensus for its use in “mild” cases, as it has little effect on other complications and carries its own risks. This study examines the cost-effectiveness of MgSO₄treatment for mild preeclampsia.

Method: We constructed a decision-analytic model to evaluate the cost-effectiveness of administration versus withholding MgSO₄ as peripartum seizure prophylaxis. We modeled a representative U.S. cohort of women with mild preeclampsia, at term gestation, to predict clinically relevant outcomes including maternal seizure, MgSO₄ toxicity, cesarean delivery, and death. Model inputs were obtained from the literature, with deliberate preference for U.S.-specific obstetric outcomes, when available. To estimate mortality reduction from treatment, we used the largest multi-national trial of MgSO₄(The Magpie Trial) and assumed the relative reductions observed abroad were also applicable to the lower U.S.-specific baseline mortality estimates. We modeled delivery events probabilistically, evaluating direct healthcare costs and decrements to quality-adjusted life years (QALYs); end-states then predicted remaining average discounted lifetime QALYs and healthcare costs based on U.S. lifetables and age-specific average medical expenditures.

Result: MgSO₄ seizure prophylaxis results in lifetime discounted QALYs of 28.189 and costs of $159,795 compared to 28.187 QALYs and $159,625 without prophylaxis, at an incremental cost of $89,420 per QALY gained, assuming a reduction in maternal mortality of 45% (as demonstrated only in data from less developed nations). Within the credible range of mortality reduction, if MgSO₄ reduces maternal death by 75% it yields benefits at a cost of $55,867 per QALY, yet with smaller mortality reductions reaches $156,356 per QALY (mortality reduction 25%). Results are also highly sensitive to the relative risk of cesarean delivery—any clinically significant increase in cesarean rates attributable to MgSO₄ensures that it is not cost-effective.

Conclusion: The cost-effectiveness of MgSO₄ in mild preeclampsia depends on assumptions about mortality and cesarean rates, which remain uncertain. Extending recommendations for routine use of MgSO₄ for mild preeclampsia is premature, given uncertain cost-effectiveness. Further data on U.S.-specific outcomes in mild preeclampsia and on MgSO₄’s impact on cesarean rates should be obtained before considering revisions of clinical guidelines.