Competing risks model in early screening for preeclampsia by biophysical and biochemical markers.
OBJECTIVE
To develop models for prediction of preeclampsia (PE) based on maternal characteristics, biophysical and biochemical markers at 11-13 weeks' gestation in which the gestation at the time of delivery for PE is treated as a continuous variable.


METHODS
This was a screening study of singleton pregnancies at 11-13 weeks including 1,426 (2.4%) that subsequently developed PE and 57,458 that were unaffected by PE. We developed a survival time model for the time of delivery for PE in which Bayes' theorem was used to combine the prior information from maternal characteristics with uterine artery pulsatility index (PI), mean arterial pressure (MAP), serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PLGF) multiple of the median (MoM) values.


RESULTS
In pregnancies with PE, there was a linear correlation between MoM values of uterine artery PI, MAP, PAPP-A and PLGF with gestational age at delivery and therefore the deviation from normal was greater for early than late PE for all four biomarkers. Screening by maternal characteristics, biophysical and biochemical markers detected 96% of cases of PE requiring delivery before 34 weeks and 54% of all cases of PE at a fixed false-positive rate of 10%.


CONCLUSIONS
A new model has been developed for effective first-trimester screening for PE.
Harris Birthright Research Centre of Fetal Medicine, King’s College Hospital, London, UK.
Ranjit
R
Akolekar
Argyro
A
Syngelaki
Leona
L
Poon
David
D
Wright
Kypros H
KH
Nicolaides
D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D005260:Female; D005865:Gestational Age; D006801:Humans; D008403:Mass Screening; D015233:Models, Statistical; D000072483:Placenta Growth Factor; D011225:Pre-Eclampsia / Q000097:blood / Q000175:diagnosis*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000097:blood*; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism*; D018570:Risk Assessment; D014463:Ultrasonography; D055988:Uterine Artery / Q000000981:diagnostic imaging
D015415:Biomarkers; C000608036:PGF protein, human; D011257:Pregnancy Proteins; D000072483:Placenta Growth Factor; D011266:Pregnancy-Associated Plasma Protein-A; C579283:PAPPA protein, human