title: Comparison of Prenatal Risk Calculation (PRC) with PIA Fetal Database software in first-trimester screening for fetal aneuploidy.
abstract: OBJECTIVE
  In February 2007 new software, Prenatal Risk Calculation (PRC), for calculating the risk of fetal aneuploidy was introduced in Germany. Our aim was to investigate its test performance and compare it with that of the PIA Fetal Database (PIA) software developed and used by The Fetal Medicine Foundation.
  
  
  METHODS
  Between 31 August 1999 and 30 June 2004 at the Women's Hospital of the Medical University of Hanover in Germany, 3120 singleton pregnancies underwent combined first-trimester screening at 11 + 0 to 13 + 6 weeks of gestation. Calculation of risk for fetal aneuploidy was computed prospectively using the PIA software. In a subsequent retrospective analysis, we recalculated risks for the 2653 of these datasets with known fetal outcome using the PRC software and compared the results.
  
  
  RESULTS
  Of the 2653 datasets analyzed, 17 were cases of aneuploidy. At a cut-off of 1 : 230, for the detection of fetal aneuploidy, the respective sensitivity, false-positive rate and positive predictive value were 70.6%, 4.1% and 9.9% for PRC and 76.5%, 2.9% and 14.6% for PIA. At a cut-off of 1 : 300, the equivalent values were 70.6%, 5.6% and 7.5% for PRC and 76.5%, 4.0% and 11.0% for PIA. The differences in test performance between the two types of software were highly significant (P < 0.0001).
  
  
  CONCLUSIONS
  The test performance of PRC was inferior to that of PIA, the sensitivity for detection of fetal aneuploidy being lower and the false-positive rate higher. Had PRC been employed prospectively in our study, 40% more women examined would have been offered unnecessarily an invasive procedure for fetal karyotyping.
authors.affiliation: Department of Obstetrics and Gynaecology, Medical University of Hanover, Hanover, Germany. cinsanchez@hotmail.com
authors.forename: C
authors.initials: C
authors.lastname: Hörmansdörfer
authors.forename: A
authors.initials: A
authors.lastname: Scharf
authors.forename: M
authors.initials: M
authors.lastname: Golatta
authors.forename: B
authors.initials: B
authors.lastname: Vaske
authors.forename: A
authors.initials: A
authors.lastname: Corral
authors.forename: P
authors.initials: P
authors.lastname: Hillemanns
authors.forename: P
authors.initials: P
authors.lastname: Schmidt
mesh_terms: D000293:Adolescent; D000328:Adult; D000782:Aneuploidy; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005858:Germany; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D012984:Software; D055815:Young Adult