Competing Risks Model in Screening for Preeclampsia by Serum Placental Growth Factor and Soluble fms-Like Tyrosine Kinase-1 at 30-33 Weeks' Gestation

OBJECTIVE: To assess the risk for preeclampsia (PE) by maternal characteristics, serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) at 30-33 weeks' gestation. METHODS: This was a screening study in singleton pregnancies including 2,140 that subsequently developed PE and 83,615 that were unaffected by PE, gestational hypertension or delivery of small-for-gestational-age neonates (normal group). We developed a survival time model for the time of delivery for PE by combination of maternal characteristics and history with PlGF and sFlt-1 multiple of the median (MoM) values (biochemical test). Data on third-trimester PlGF and sFlt-1 were available in 118 cases of PE and 3,734 of normal group. The detection rate (DR) of PE requiring delivery within 4, 6 and 8 weeks of the visit was estimated. RESULTS: In pregnancies with PE, the log10 MoM values of PlGF and sFlt-1 were linearly related to gestational age at delivery. Screening by the biochemical test detected 100, 76, and 62% of PE with delivery within 4, 6 and 8 weeks of the visit, at a fixed false-positive rate of 5%. INTERPRETATION: Testing by PlGF and sFlt-1 at 30-33 weeks could identify all pregnancies developing PE and requiring delivery within the subsequent 4 weeks.