Evaluation of screening performance of first trimester competing risk prediction model for small for gestational age in Asian population

OBJECTIVES: To examine the external validity of the new Fetal Medicine Foundation (FMF) competing risk model for the prediction of small for gestational age (SGA) at 11-14 weeks of gestation in Asian population.

METHODS: This is a secondary analysis of a multicenter prospective cohort study in 10,120 women with singleton pregnancies undergoing routine assessment at 11-14 weeks of gestation. We applied the FMF competing risk model for the first-trimester prediction of SGA combining maternal characteristics and medical history with measurements of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), and serum placental growth factor (PlGF). We obtained risks for different cut-offs of birth weight percentile and gestational age at delivery. We examined the predictive performance in terms of discrimination and calibration.

RESULTS: The predictive performance of the competing risk model for SGA was similar to that reported in the FMF study. Specifically, the combination of maternal factors with MAP, UtA-PI, and PlGF yielded the best performance for the prediction of preterm SGA <10 th percentile (SGA<10 th ) and preterm SGA <5 th percentile (SGA<5 th ), with the areas under the curves (AUCs) of 0.765 (95% confidence interval [CI], 0.720-0.809) and 0.789 (95%CI, 0.736-0.841), respectively. Combining maternal factors, MAP, and PlGF yielded the best model for predicting preterm SGA <3 rd percentile (SGA<3 rd ), with an AUC of 0.797 (95%CI, 0.744-0.850). After excluding preeclampsia (PE) cases, the combination of maternal factors with MAP, UtA-PI, and PlGF yielded the best performance for the prediction of preterm SGA<10 th and SGA<5 th , with AUCs of 0.743 (95%CI, 0.691-0.795) and 0.762 (95%CI, 0.700-0.824), respectively. However, the best model for predicting preterm SGA<3 rd without PE was the combination of maternal factors and PlGF, with an AUC of 0.786 (95%CI, 0.723-0.849). The FMF competing risk model including maternal factors, MAP, UtA-PI, PlGF achieved DRs of 42.2%, 47.3%, and 48.1%, at the fixed FPR of 10%, for the prediction of preterm SGA with birth weight <10 th , 5 th and 3 rd percentiles, respectively. The calibration of the new model was satisfactory.

CONCLUSION: The screening performance of the new FMF first trimester competing risk model for SGA in an independent large cohort of Asian women is comparable to that reported in the original FMF study on a mixed European population. This article is protected by copyright. All rights reserved.