title: Down syndrome screening in the first and/or second trimester: model predicted performance using meta-analysis parameters.
abstract: OBJECTIVE
  To predict the screening performance for 17 policies currently in use or being considered for the near future.
  
  
  METHODS
  Multivariate Gaussian modeling using parameters derived from published meta-analyses and new meta-analyses for gestation-specific nuchal translucency and between trimester correlations.
  
  
  RESULTS
  For a 1% to 5% false-positive rate, first trimester screening achieved detection rates up to 16% to 25% higher than the best second trimester combination. Screening in both trimesters sequentially could yield an even greater increase in detection of 24% to 35%. The most efficient sequential policy was contingent screening, which has a high detection rate with only 15% of women needing second trimester tests.
  
  
  CONCLUSIONS
  Modeling with meta-analysis derived parameters provides a reliable guide for policy and favors a contingent screening policy. The widespread practice of calculating first and second trimester risks separately should be abandoned.
authors.affiliation: University of Leeds, Leeds, UK. h.s.cuckle@leeds.ac.uk
authors.forename: Howard
authors.initials: H
authors.lastname: Cuckle
authors.forename: Peter
authors.initials: P
authors.lastname: Benn
authors.forename: Dave
authors.initials: D
authors.lastname: Wright
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D004964:Estriol / Q000097:blood; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis*; D005333:Fetus; D006801:Humans; D008423:Maternal Age; D015201:Meta-Analysis as Topic; D015233:Models, Statistical; D015999:Multivariate Analysis; D016011:Normal Distribution; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D011296:Prenatal Diagnosis / Q000379:methods* / Q000592:standards; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D011266:Pregnancy-Associated Plasma Protein-A; D004964:Estriol