Using maternal characteristics to identify high-risk pregnant women for second-stage preeclampsia screening achieved similar detection rates as screening all pregnant women, based on data from a prospective study of 61,174 singleton pregnancies.

About 90% of preeclampsia cases can be predicted using the “triple test” of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF) plus a combination of maternal factors at 11 to 13 weeks’ gestation, wrote Alan Wright, PhD, of the University of Exeter, United Kingdom, and colleagues. The need for detection of preeclampsia is important, as high-risk pregnant women who take aspirin before 16 weeks’ gestation can reduce early preeclampsia by 90% and preterm preeclampsia by 60%, they said.

However, “measurements of serum PlGF and UtA-PI are not part of routine care and would be associated with an additional cost,” Dr. Wright and his colleagues noted in the American Journal of Obstetrics & Gynecology.

In the study, the researchers used a competing risks model to combine MAP, UtA-PI, and PlGF and maternal factors to compare detection rates if the triple test were used for a subset of high-risk women. Most of the women in the study were white.

Overall, Dr. Wright and his colleagues found, if first-stage screening method is maternal factors, then measurements of MAP, UtA-PI, and PlGF can be reserved for 70% of the pregnant population.

When the researchers compared various components of the triple test, they found that, if the first stage of screening included maternal factors along with MAP and UtA-PI, measurement of PlGF could be saved for 30%-40% of pregnant women. Similarly, if first-stage screening included maternal factors, MAP, and PlGF, measurement of UtA-PI can be saved for 20%-30% of the population, they said.

The study findings were limited by several factors, including the homogeneity of the population studied, the researchers noted. “The risk for development of [preeclampsia] is higher in women of black or South Asian racial origin than in white women,” Dr. Wright and his colleagues wrote. “Consequently, in screening in a population of mixed racial origins, for a given risk cut-off, the [detection rate] and [screen positive rate] would be higher in black and South Asian than white women and the overall performance would be dependent on the proportion of the various racial groups within that population.”

However, the results support the effectiveness of using only certain tests paired with maternal factors to identify high-risk patients for further screening.

“Inevitably, biomarker screening for only part of the population will have financial benefits over conducting the test for the entire population,” the researchers said.

Dr. Wright and his colleagues reported no conflicts of interest. The study was supported in part by the Fetal Medicine Foundation, and the reagents and equipment used for the measurement of serum placental growth factor were provided by PerkinElmer Life and Analytical Sciences.

SOURCE: Wright A et al. Am J Obstet Gynecol. 2018. doi: 10.1016/j.ajog.2018.10.092.