The QUIPP app: a safe alternative to a treat-all strategy for threatened preterm labour

OBJECTIVES: To evaluate the impact of a treat-all policy (advocated by NICE) compared to the QUIPP app (predictive model combining history of spontaneous preterm birth gestation and quantitative fetal fibronectin) for women in threatened preterm labour at <30 weeks gestation.

METHODS: We conducted a subanalysis of prospectively collected data of pregnant women presenting with symptoms of preterm labour from the EQUIPP (REC Ref. 10/H0806/68) and PETRA (REC Ref. 14/LO/1988) research database. Women between 24 and 34 weeks of gestation in suspected labour at a tertiary inner-city hospital (abdominal pain or tightenings) were identified. Each episode was retrospectively assigned a risk of birth within 7 days using the QUIPP app. A primary outcome of delivery within 7 days was used to model the accuracy of the QUIPP app compared with a treat-all policy..

RESULTS: With a risk threshold of 5% (of delivery within 7 days) to treat, 9/9 women would have been correctly treated giving a sensitivity of 100% (one-sided 97.5% CI 0.664) and a negative predictive value PV of 100% (CI 98.9 to 100%). The positive predictive value was 30% (95% CI 4.3 to 49.1%) before 30 weeks and 20% (CI 11.9 to 54.3%) between 30 and 34 weeks. If this 5% threshold had been used to triage women between 24 and 29(+6) weeks, 89% of admissions (168) could have been safely avoided compared to 0% with a treat-all strategy. No true cases would have been missed as none of the women who were given a risk less than 10% delivered within 7 days.

CONCLUSION: For women in threatened preterm labour, the QUIPP app can accurately guide management at risk thresholds of 1%, 5% and 10%, allowing outpatient management for the vast majority. A treat-all approach, would have protected none, exposed 188 mothers and babies to unnecessary hospitalisation and steroids, and increased the burden on networks and transport services due to unnecessary in-utero transfers. Prediction should be used before 30 weeks to determine management until there is evidence that such high levels of unnecessary intervention do less harm than the rare false negatives.