title: Repeat maternal serum testing for Down's syndrome screening using multiple markers with special reference to free alpha and free beta-hCG.
abstract: To determine the effect of routine repeat testing in serum screening for Down's syndrome, we compared estimates of the detection and false-positive rates. Five serum markers were measured--alpha-fetoprotein (AFP), unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG), and its two subunits, free alpha and free beta-hCG. First and repeat test marker levels were available from 142 women whose samples had been routinely collected and stored in an antenatal serum bank. Different repeat testing policies were compared for various combinations of the markers. If all women had repeat tests using the four markers AFP, uE3, and free alpha and free beta-hCG, the detection rate for a 5 per cent false-positive rate was 69 per cent compared with 65 per cent if no women were repeated. Policies of repeating selected women gave similar results. The small gain in screening performance with repeat testing performed routinely is not worthwhile. If a woman does happen to have a repeat test, her risk estimate should, however, be based on both results, not just the second.
authors: Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, Medical College of St Bartholomew's Hospital, Charterhouse Square, London, U.K.
authors: A K
authors: AK
authors: Hackshaw
authors: J
authors: J
authors: Densem
authors: N J
authors: NJ
authors: Wald
mesh_terms: D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood*; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods* / Q000706:statistics & numerical data; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D015292:Glycoprotein Hormones, alpha Subunit