Prenatal reflex DNA screening for Down syndrome: enhancing the screening performance of the initial first trimester test. (28th February 2016)

• Record Type: Journal Article
• Authors: Wald, Nicholas J.; Bestwick, Jonathan P.
• Is Part Of: Prenatal diagnosis. Volume 36:Number 4(2016)
• Page Start: 328
• Page End: 331
• Publication Date: 2016-02-28
• Subjects: Prenatal diagnosis -- Periodicals; Fetus -- Diseases -- Diagnosis -- Periodicals; Electronic journals; 618.32075
• DOI: 10.1002/pd.4784
• Languages: English
• ISSNs: 0197-3851

Abstract

Abstract: Objective: To estimate the effect of adding three biochemical markers (alphafetoprotein, inhibin‐A, and placental growth factor) and two ultrasound markers (ductus venosus pulsatility index and nasal bone examination) to enhance the initial Combined test in prenatal reflex DNA screening for Down syndrome. Methods: Published data were used to estimate screening performance [detection rates (DRs) and false‐positive rates (FPRs)] of reflex DNA screening according to the additional markers used, the proportion of women with the highest initial test risks reflexed to DNA testing and the gestational age at the time of blood collection. Results: If 10% of women are reflexed, the addition of the three biochemical markers to the Combined test increases the DR from 90.8% to 92.3% (FPR 0.025% to 0.027%) with markers measured at 11 completed weeks' gestation. With markers measured at 13 completed weeks' gestation the DR increases from 87.7% to 95.2% (FPRs both 0.027%). The further addition of the two ultrasound markers increases the DR to 96.8% and 97.5% at 11 and 13 weeks' respectively (FPR to 0.024% and 0.022% respectively). Conclusion: Adding the specified markers to the Combined test can maintain or improve screening performance with a lower proportion of women reflexed. Our results can be used to determine the most cost‐effective reflex DNA screening policy. © 2016 John Wiley & Sons, Ltd. Abstract : What's Already Known About This Topic? Prenatal reflex DNA screening for Down syndrome has a high detection rate and a very low false‐positive rate. This form of screening has been introduced into routine practice. What Does This Study Add? Adding biochemical and/or ultrasound markers to the initial Combined test reduces the proportion of women who need to be reflexed to a DNA test to achieve the same overall screening performance. Estimates of screening performance and risk cut off levels are specified for adding biochemical markers (alphafetoprotein, inhibin‐A, and placental growth factor) and ultrasound markers (ductus venosus pulsatility index and nasal bone examination) to the first trimester Combined test.