Risk assessment for preeclampsia in nulliparous women at 11-13 weeks gestational age: prospective evaluation of two algorithms.

OBJECTIVE: To evaluate two algorithms for prediction of preeclampsia in a population of nulliparous women in Norway.
DESIGN: Prospective screening study.
SETTING: National Centre for Fetal Medicine in Trondheim, Norway. POPULATION: Five hundred and forty-one nulliparous women.
METHODS: The women were examined between 11(+0) and 13(+6) weeks with interviews for maternal characteristics and measurements of mean arterial pressure, uterine artery pulsatility index, pregnancy-associated plasma protein A and placental growth factor. The First Trimester Screening Program version 2.8 by The Fetal Medicine Foundation (FMF) was compared with the Preeclampsia Predictor TM version 1 revision 2 by Perkin Elmer (PREDICTOR). MAIN OUTCOME MEASURES: Prediction of preeclampsia requiring delivery before 37 weeks, before 42 weeks and late preeclampsia (delivery after 34 weeks).
RESULTS: The performance of the two algorithms was similar, but quite poor, for prediction of preeclampsia requiring delivery before 42 weeks with an area under the curve of 0.77 (0.67-0.87) and sensitivity 40% (95% CI 19.1-63.9) at a fixed 10% false positive rate for FMF and 0.74 (0.63-0.84) and sensitivity 30% (95% CI 11.9-54.3) at a fixed 10% false positive rate for PREDICTOR. The FMF algorithm for preeclampsia requiring delivery <37 weeks had an area under the curve of 0.94 (0.86-1.0) and sensitivity of 80% (95% CI 28.4-99.5) at a 10% fixed false positive rate.
CONCLUSIONS: Fetal Medicine Foundation and PREDICTOR algorithms had similar and only modest performance in predicting preeclampsia. The results indicate that the FMF algorithm is suitable for prediction of preterm preeclampsia.