Predictive performance for placental dysfunction related stillbirth of
the competing risks model for small for gestational age fetuses
Abstract
Objectives: First, to examine the predictive performance for placental
dysfunction related stillbirths of the competing risks model for small
for gestational age (SGA) fetuses based on a combination of maternal
risk factors, estimated fetal weight (EFW) and uterine artery
pulsatility index (UtA-PI); and second, to compare the performance of
this model to that of stillbirth-specific model utilizing the same
biomarkers and to the Royal College of Obstetricians and Gynecologists
(RCOG) guideline for the investigation and management of the SGA fetus.
Design: Prospective observational study. Setting: Two UK maternity
hospitals. Population: 131,514 women with singleton pregnancies
attending for routine ultrasound examination at 19-24 weeks’ gestation.
Methods: The predictive performance for stillbirth achieved by three
models was compared. Main outcome measures: Placental dysfunction
related stillbirth. Results: At 10% false positive rate, the competing
risks model predicted 59%, 66% and 71% of placental dysfunction
related stillbirths, at any gestation, at <37 weeks and at
<32 weeks, respectively, which were similar to the respective
figures of 62%, 70% and 73% for the stillbirth-specific model. At a
screen positive rate of 21.8 %, as defined by the RCOG guideline, the
new model predicted 71%, 76% and 79% of placental dysfunction related
stillbirths at any gestation, at <37 weeks and at
<32 weeks, respectively, and the respective figures for the
RCOG guideline were 42%, 44% and 40%. Conclusion: The predictive
performance for placental dysfunction related stillbirths by the
competing risks model for SGA was similar to the stillbirth-specific
model and superior to the RCOG guideline.