When to Treat for Preterm Labor

ABSTRACT & COMMENTARY

Synopsis: With a probability of neonatal respiratory distress syndrome of less than 2% or beyond 36 weeks gestation, it was most cost-effective not to treat patients in preterm labor.

Source: Myers ER, et al. Obstet Gynecol 1997;90:824-829.

To determine the cost-effectiveness of strategies to reduce the risk of neonatal respiratory distress syndrome (RDS) resulting from idiopathic preterm labor, Myers and associates analyzed the hospital costs associated with three options: 1) tocolysis and treatment with corticosteroids; 2) amniocentesis and testing for fetal lung maturity with the TDX FLM assay; and 3) no treatment. Corticosteroids were assumed to reduce the risk of RDS by 65% after 24 hours of treatment. Median total hospital costs for admission to the neonatal intensive care unit for the treatment of RDS were $25,000. The analysis did not include confounding factors such as ruptured membranes, chorioamnionitis, maternal disease, or other causes of preterm birth. Because the analysis was based on data from a tertiary medical center with a neonatal intensive care unit, the costs of maternal transfer, neonatal transfer, or both were not considered.

The probability of RDS and the costs of caring for RDS were the most important factors in determining the most cost-effective strategy. Above a probability of RDS of 17% or before 34 weeks gestation, treating all patients with tocolysis and corticosteroids was most cost-effective. With a probability of RDS between 2-17% or between 34-36 weeks, performing an amniocentesis to determine fetal lung maturity before treating was most cost-effective. With a probability of RDS of less than 2% or beyond 36 weeks gestation, it was most cost-effective not to treat patients in preterm labor.

COMMENT BY STEVEN G. GABBE, MD

Myers et al have provided helpful guidelines to determine the most cost-effective strategy for managing patients with idiopathic preterm labor. While the information on the costs of care has been derived from a single tertiary care institution, the analysis was based on the best available information on the probability of RDS, the efficacy of corticosteroids in reducing this risk, and the ability of tocolysis to delay delivery by 48 hours. Certainly, the analysis does not apply to all populations or all patients presenting with preterm labor, nor does it consider the non-RDS costs of preterm birth. Yet, these recommendations for the most cost-effective approach should be considered: before 34 weeks gestation, tocolytics and corticosteroids; between 34-36 weeks, testing for fetal lung maturity; and, after 36 weeks, no treatment. (Dr. Gabbe is Professor and Chairman, Department of OB/GYN, University of Washington School of Medicine, Seattle.)