The majority (85%–95%) of women presenting with symptoms of preterm labor before 34 weeks' gestation in developed countries do not deliver within 1 week of presentation. As transfer and subsequent treatment lead to substantial costs, in addition to maternal anxiety with adverse effects for both the mother and the unborn child, the researchers sought to appropriately identify women at low risk of immediate preterm delivery, which could reduce unnecessary interventions in these women that ultimately may result in cost savings and reduced discomfort and adverse effects.
The model-based cost-effectiveness analysis included women with symptoms of preterm labor, intact membranes, and a gestational age between 24 and 34 weeks. All women in the model had symptoms of preterm labor (contractions >3 per 30 minutes, vaginal bleeding, or abdominal or back pain), such that they would be tested for CL and fFN. Treatment consisted of administration of tocolysis and steroids, combined with transfer of women to a perinatal center if they were in a general hospital. Preterm delivery was defined as delivery within 7 days of presentation, because this outcome is related to the need for immediate transfer to a perinatal center, hospitalization, and treatment. Researchers also distinguished between women who would deliver before 34 weeks and those who would deliver after 34 weeks, which allowed for an assessment of differences in health-related neonatal outcomes and costs.
Seven test-treatment strategies were evaluated: (1) a treat-all, reference strategy that consisted of treating all women with symptoms of preterm labor with tocolysis and steroids and transferring them to a tertiary center; (2) treat if CL is less than 25 mm; (3) treat if fFN test is positive; (4) treat if fFN test is positive and CL is less than 25 mm; (5) treat if either fFN test is positive or CL is less than 25 mm; (6) treat if CL is less than 15 mm or perform fFN test if CL is between 15 and 30 mm and treat if fFN test is positive; and (7) no treatment. The 5 management schemes (strategies 2–6) incorporated risk assessment with fFN testing and/or CL measurement.
This study found that strategies using fFN testing and CL measurement separately to predict preterm delivery are associated with higher costs and incidence of adverse neonatal outcomes compared with strategies that combine both tests. Additional fFN testing when CL is 15 to 30 mm was considered cost-effective, leading to a cost saving of €3919 per woman when compared with a treat-all strategy, with a small deterioration in neonatal health outcomes, namely, 1 additional perinatal death and 21 adverse outcomes per 10,000 women with signs of preterm labor (incremental cost-effectiveness ratios €39 million and €1.9 million, respectively). Implementing this strategy in the Netherlands, a country with approximately 180,000 deliveries annually, could lead to an annual cost saving of between €2.4 million and €7.6 million, with only a small deterioration in neonatal health outcomes. Ultimately, in women with symptoms of preterm labor at 24 to 34 weeks' gestation, performing additional fFN testing when CL is between 15 and 30 mm is a viable and cost-saving strategy.