Predicting preterm birth: a cost-effectiveness analysis

The objective of this study was to compare the cost-effectiveness of 9 strategies for the management of threatened preterm labor.

We derived 6 management options from the literature. These were (1) to treat all women with tocolytics and corticosteroids ("treat all"); (2) to treat all women while awaiting results of the "traditional" fetal fibronectin test results, then discontinue treatment on those with negative results; (3) to treat only those with abnormal cervical length measurements as detected by ultrasonography; (4) to treat only those with abnormal "rapid" fetal fibronectin test results; (5) to perform rapid fetal fibronectin testing and cervical length measurements and treat those with a positive result on either or both; (6) not to treat any women ("treat none"). To assess the contributions of tocolytics and corticosteroids to our outcomes, we analyzed 3 additional treatment options: (7) to treat all women with outpatient corticosteroids but not give tocolytics, (8) to administer corticosteroids to all but give tocolytics only to those with abnormal rapid fetal fibronectin test results, and (9) to administer corticosteroids to all but give tocolytics only to those with abnormal cervical length. We used decision analytic techniques to perform a cost-effectiveness analysis.

A decision tree was constructed on the basis of these strategies. We reviewed the literature to derive all probability information. We derived sensitivity and specificity for delivery <37 weeks for fetal fibronectin and for abnormal cervical length. Outcomes of interest were respiratory distress syndrome and neonatal death. We derived cost variables from institutional statistics and from values quoted in the literature. Total costs, cases of respiratory distress syndrome, neonatal deaths, and cost-effectiveness ratios were calculated for each of the strategies. We conducted sensitivity analyses on all variables. Universal administration of outpatient corticosteroids was the least expensive option, but it resulted in more cases of respiratory distress syndrome and deaths than "treat all." Rapid fetal fibronectin plus corticosteroids, traditional fetal fibronectin, and cervical length plus corticosteroids were the next least expensive options and resulted in numbers of cases of respiratory distress syndrome and deaths that were similar to those in the "treat all" strategy. The "rapid" fetal fibronectin test, cervical length measurement, rapid fetal fibronectin test plus cervical length measurement, and "treat none" strategies resulted in more respiratory distress syndrome, more deaths, and higher costs. Treating all patients resulted in the fewest number of cases of respiratory distress syndrome and deaths but the greatest costs.

Risk prediction strategies with the fetal fibronectin assay or corticosteroids plus rapid fetal fibronectin testing or cervical length assessment may offer cost savings compared with treatment of all women with threatened preterm labor and may prevent similar numbers of cases of respiratory distress syndrome and neonatal deaths.