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Combining first and second trimester markers for Down syndrome screening: Think twice
Author(s) -
COCCIOLONE Robert,
BRAMELD Kate,
O’LEARY Peter,
HAAN Eric,
MULLER Peter,
SHAND Karen
Publication year - 2008
Publication title -
australian and new zealand journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.734
H-Index - 65
eISSN - 1479-828X
pISSN - 0004-8666
DOI - 10.1111/j.1479-828x.2008.00911.x
Subject(s) - second trimester , first trimester , down syndrome , medicine , false positive rate , population , obstetrics , pregnancy , gynecology , computer science , gestation , biology , psychiatry , genetics , environmental health , artificial intelligence
Aims: This study compares different screening strategies for the detection of Down syndrome and considers practical implications of using multiple screening protocols. Methods: The performance characteristics of each screening strategy were assessed based on datasets of Down syndrome ( n = 11) and unaffected pregnancies ( n = 1006) tested in both first and second trimester, as well as data from first trimester ( n = 18 901) and second trimester ( n = 40 748) pregnancies. Results: For a detection rate of 91%, the false positive rates for integrated and serum integrated screening were 2.5% and 6.3%, respectively, compared with combined first trimester (4.6%) and second trimester (12.6%) screening. Contingent and sequential screening protocols achieved detection rates of 82 to 91% with false positive rates between 2.6 and 2.9%. Contingent protocols require retesting of 15 to 20% of cases in the second trimester. Sequential and integrated protocols require retesting of 98 to 100% of cases in the second trimester. The various screening strategies did not always detect the same Down syndrome pregnancies. Conclusions: Combining first and second trimester markers for Down syndrome screening better defines the at‐risk population. However, integrated protocols complicate management of screening programs and may not be suitable as primary screening strategies. It may be a better use of resources to refine current first and second trimester programs through improved access and new markers. We therefore suggest thinking twice before embracing integrated population screening programs.