Competing risks model in screening for preeclampsia by biophysical and biochemical markers at 30-33 weeks' gestation.

OBJECTIVE To assess the risk for preeclampsia (PE) by maternal characteristics, uterine artery pulsatility index (Ut-PI), mean arterial pressure (MAP), 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 developed PE and 83,615 that were unaffected by PE. We developed a survival time model for the time of delivery for PE by combining maternal characteristics and history with Ut-PI, MAP, PlGF and sFlt-1 multiple of the median (MoM) values (combined test). Data on third-trimester MAP and Ut-PI were available in 350 cases of PE, and 13,878 unaffected pregnancies and data on PlGF and sFlt-1 were available in 118 cases of PE and 3,734 unaffected pregnancies. Modelled detection rate of all PE and PE requiring delivery within 4 and 6 weeks of the visit was estimated. RESULTS Screening by the combined test would detect 66, 98 and 86% of all PE and PE requiring delivery within 4 and 6 weeks of the visit, respectively, at a false positive rate of 5%. INTERPRETATION Screening by biophysical and biochemical testing at 30-33 weeks could identify most pregnancies developing PE and requiring delivery within the subsequent 4 weeks.