COST EFFECTIVENESS OF ANTENATAL STEROIDS IN LATE PRETERM PREGNANCIES

Purpose: Recent increases in the preterm birth rate are due in large part to an increase in “late preterm births”, defined as deliveries between 34 and 37 weeks gestation; the late preterm delivery rate has risen 25% since 1990.  The single most effective intervention to reduce the morbidity and mortality associated with preterm birth prior to 34 weeks has been antenatal glucocorticoid administration; however, this intervention is not usually administered after 34 weeks.  We sought to investigate the potential cost effectiveness of administering steroids to women at risk for late preterm delivery. 

Method: Decision-analytic models were developed to consider hypothetical cohorts of women at 34, 35, or 36 weeks at risk for preterm birth.  Two management strategies were considered: (1) universal steroid administration and (2) expectant management.  Baseline assumptions included a rate of RDS of 15%, 13%, and 4% at 34, 35, and 36 weeks, respectively, and a 33% reduction in RDS with steroid administration.  Analysis consisted of examining the rates of respiratory distress syndrome and neonatal demise that would occur with each strategy and calculating the incremental cost effectiveness ratio of each strategy from a societal perspective.  Deterministic one-way and multi-way sensitivity analyses were performed to identify key parameters and examine the robustness of the findings.  Probabilistic sensitivity analysis (via a Monte Carlo simulation) was performed to test the model’s robustness to simultaneous multivariable changes.   

Result: Steroid administration was the dominant option at 34 weeks, as it was more effective and less costly than expectant management.  At 35 weeks, steroid administration remained cost-effective, but at 36 weeks it was not.  These findings were sensitive to variation in the likelihood of delivery within 48 hours and the effectiveness of steroids in reducing morbidity. 

Conclusion: For women presenting at risk of delivery between 34 and 37 weeks, steroid administration may reduce neonatal morbidity and be cost effective.  The efficacy of steroids in the late preterm gestation deserves further prospective investigation.  Late preterm infants account for more than 70% of infants that are delivered preterm; any intervention to decrease the morbidity of infants born during this period has the potential to have a significant impact on the health care system, and the overall prevalence rate of morbidity due to prematurity.