Abstract | OBJECTIVES: In prenatal screening for Down syndrome, serum marker values can be adjusted using values from a previous pregnancy to avoid the problem of women having a high chance of recurrent false-positive results. We investigate the effect of such adjustment on overall screening performance. METHODS: Monte Carlo simulation was used to investigate the effect of this adjustment on five widely used screening tests for Down syndrome (Triple, Quadruple, Combined, serum Integrated, Integrated tests). RESULTS: Adjustment for screening marker values (expressed in multiples of the median, (MoM)) in a previous pregnancy improved screening performance. The detection rate for a 1% false-positive rate (FPR) increased from 54 to 59% with the Triple test, from 63 to 68% with the Quadruple test, from 70 [corrected] to 75% for the Combined test, from 70 [corrected] to 76% for the serum Integrated test, and from 85 to 88% for the Integrated test. The FPR for an 85% detection rate decreased from 10 to 7.9%, 7.1 to 4.9%, 4.9 to 3.7%, 4.7 to 2.9% and 1.1 to 0.7% respectively for the five tests. Among women who have had a false-positive result in a previous pregnancy, adjustment substantially lowers the false-positive rate, for example, from 18 [corrected] to 7.3% with the Combined test using a 1 in 250 risk cut-off. CONCLUSION: MoM adjustment for values in a previous pregnancy improves overall screening performance and substantially reduces the high recurrent false-positive rate. This adjustment can be routinely applied in screening programmes through the screening software used to interpret a woman's screening results.
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Authors | Nicholas J Wald, Isobel M Barnes, Ruthie Birger, Wayne Huttly |
Journal | Prenatal diagnosis
(Prenat Diagn)
Vol. 26
Issue 6
Pg. 539-44
(Jun 2006)
ISSN: 0197-3851 [Print] England |
PMID | 16634123
(Publication Type: Evaluation Study, Journal Article)
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Copyright | Copyright 2006 John Wiley & Sons, Ltd. |
Chemical References |
- Biomarkers
- Chorionic Gonadotropin, beta Subunit, Human
- Pregnancy-Associated Plasma Protein-A
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Topics |
- Adolescent
- Adult
- Biomarkers
(blood)
- Chorionic Gonadotropin, beta Subunit, Human
(blood)
- Down Syndrome
(diagnosis, embryology)
- False Positive Reactions
- Female
- Gestational Age
- Gravidity
- Humans
- Maternal Age
- Middle Aged
- Models, Theoretical
- Nuchal Translucency Measurement
(methods, statistics & numerical data)
- Pregnancy
- Pregnancy Trimester, First
(blood)
- Pregnancy Trimester, Second
(blood)
- Pregnancy-Associated Plasma Protein-A
(analysis)
- Prenatal Diagnosis
(methods)
- Risk Adjustment
(methods)
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