The QUiPP App: a safe alternative to a treat-all strategy for threatened preterm labor

To evaluate the impact of triaging women at risk of spontaneous preterm birth (sPTB) using the QUiPP App, which incorporates a predictive model combining history of sPTB, gestational age and quantitative measurements of fetal fibronectin, compared with a treat-all policy (advocated by the UK National Institute for Health and Care Excellence) among women with threatened preterm labor before 30 weeks' gestation.

Prospectively collected data of pregnant women presenting with symptoms of preterm labor (abdominal pain or tightening) at 24-34 weeks' gestation were retrieved from the research databases of the EQUIPP and PETRA studies for subanalysis. Each episode of threatened preterm labor was retrospectively assigned a risk for sPTB within 7 days using the QUiPP App. A primary outcome of delivery within 7 days was used to model the performance accuracy of the QUiPP App compared with a treat-all policy.

Using a 5% risk of delivery within 7 days according to the QUiPP App as the threshold for intervention, 9/9 women who presented with threatened preterm labor < 34 weeks would have been treated correctly, giving a sensitivity of 100% (one-sided 97.5% CI, 66.4%) and a negative predictive value of 100% (97.5% CI, 98.9-100%). The positive predictive value for delivery within 7 days was 30.0% (95% CI, 11.9-54.3%) for women presenting before 30 weeks and 20.0% (95% CI, 12.7-30.1%) for women presenting between 30 + 0 and 34 + 0 weeks. If this 5% threshold had been used to triage women presenting between 24 + 0 and 29 + 6 weeks, 89.4% (n = 168) of admissions could have been safely avoided, compared with 0% for a treat-all strategy. No true case of preterm labor would have been missed, as no woman who was assigned a risk of < 10% delivered within 7 days.

For women with threatened preterm labor, the QUiPP App can accurately guide management at risk thresholds for sPTB of 1%, 5% and 10%, allowing outpatient management in the vast majority of cases. A treat-all approach would not have avoided admission for any woman, and would have exposed 188 mothers and their babies to unnecessary hospitalization and steroid administration and increased the burden on network and transport services owing to unnecessary in-utero transfers. Prediction of sPTB should be performed before 30 weeks to determine management until there is evidence that such a high level of unnecessary intervention, as suggested by the treat-all strategy, does less harm than the occurrence of rare false negatives. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.