Antenatal Screening for Down Syndrome Using Serum Placental Growth Factor with the Combined,Quadruple, Serum Integrated and Integrated Tests |
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Authors: | Nicholas J. Wald Jonathan P. Bestwick Lynne M. George Wayne J. Huttly |
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Affiliation: | Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.; The University of Texas M. D. Anderson Cancer Center, United States of America, |
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Abstract: | ObjectiveTo estimate the value of first or second trimester placental growth factor (PlGF) as an additional antenatal screening marker for Down syndrome.DesignNested case-control study.SettingAntenatal screening service.Population or Sample532 Down syndrome pregnancies and 1,155 matched unaffected pregnancies.MethodsStored maternal serum samples (−40°C) were assayed for PlGF. Monte Carlo simulation was used to estimate the screening performance of PlGF with the Combined, Quadruple, serum Integrated and Integrated tests.Main Outcome MeasuresMedian PlGF levels in affected and unaffected pregnancies and screening performance (detection rates [DR] for specified false-positive rates [FPR] and vice versa).ResultsFirst trimester median PlGF was 15%, 28% and 39% lower in Down syndrome than unaffected pregnancies at 11, 12 and 13 completed weeks’ gestation respectively (all p<0.001). Second trimester median PlGF was 31% lower at 14 weeks (p<0.001), and the difference decreased (6% lower at 17 weeks). At a 90% DR with first trimester markers measured at 13 weeks, adding PlGF decreased the FPR from 11.1 to 5.1% using the Combined test, 9.3% to 4.5% using the serum Integrated test, and 3.4% to 1.5% using the Integrated test (or 1.5 to 1.4% with first trimester markers measured at 11 weeks). Adding PlGF to the Quadruple test (measured at 15 weeks) decreased the FPR from 10.0% to 9.6% at a 90% DR.ConclusionsFirst trimester PlGF measurements improve the performance of antenatal screening for Down syndrome using the Combined, serum Integrated and Integrated tests. Second trimester PlGF measurements are of limited value. |
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