title: First-trimester Down syndrome screening performance in the Dutch population; how to achieve further improvement?
abstract: OBJECTIVE
  To study the performance of the first-trimester combined test between 2004 and 2006 compared to a previous period to investigate changes in time and identify reasons for sub-optimal performance.
  
  
  METHODS
  Serum samples were analysed for pregnancy-associated plasma protein A (PAPP-A) and the free beta subunit of human chorionic gonadotrophin (f beta-hCG). Nuchal translucency (NT) was measured between 10 and 14 weeks. Tests were considered screen positive, if their calculated Down syndrome (DS) risk was at least 1 in 250 at term.
  
  
  RESULTS
  A total of 20,293 singleton pregnancies were included in the analysis. The median maternal age fell from 35.7 to 34.3 years. The overall median weight-corrected multiple of the median (MoM) values of PAPP-A and f beta-hCG were 1.12 and 1.03, respectively. The median MoM value of NT was 0.89 and increased from 0.82 to 0.96. Sixty-six DS cases were detected by the screening test. The detection rate (DR) for DS was 75.9%, with a FPR of 3.3%.
  
  
  CONCLUSIONS
  The performance of the first-trimester test has improved over the years. A better performance of the NT measurement was the main reason, although NT assessment should further be improved. In addition, a better setting of the medians for the biochemical parameters may contribute to a higher DR.
authors.affiliation: Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Lundlaan 6, 3508 AB Utrecht, The Netherlands. E.Wortelboer@umcutrecht.nl
authors.forename: E J
authors.initials: EJ
authors.lastname: Wortelboer
authors.forename: M P H
authors.initials: MP
authors.lastname: Koster
authors.forename: Ph
authors.initials: P
authors.lastname: Stoutenbeek
authors.forename: L H
authors.initials: LH
authors.lastname: Elvers
authors.forename: J G
authors.initials: JG
authors.lastname: Loeber
authors.forename: G H A
authors.initials: GH
authors.lastname: Visser
authors.forename: P C J I
authors.initials: PC
authors.lastname: Schielen
mesh_terms: D000293:Adolescent; D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009426:Netherlands; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D055815:Young Adult
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A