title: Aneuploidy screening during pregnancy by a three-dimensional Advanced First Trimester Screening model: description of the AFS-3D algorithm.
abstract: BACKGROUND
  A novel screening method for fetal aneuploidies was developed, in which nuchal translucency (NT), pregnancy-associated plasma protein-A (PAPP-A), and free-β human chorionic gonadotropin (free-β hCG) are placed into a three-dimensional scatter plot. Likelihood ratios are directly inferred from the ratio of already observed healthy and diseased fetuses. This method is called 'Three-dimensional Advanced First trimester Screening' (AFS-3D). It was aimed to develop and test a new algorithm based on the results of previous studies.
  
  
  METHODS
  A new static-sized sphere model was developed. Several scaling factors of the axes and the optional application of the modifications 'simulation' (SIM) and 'empty sphere positive' were tested on 15,227 data sets. An additional examination was performed on a second collective (n = 458).
  
  
  RESULTS
  The application of the new AFS-3D model with static-sized spheres, a re-sampled ∆NT axis by a scaling factor of 0.125, and the application of SIM and Empty Box Positive resulted in a marked improvement of the test performance (area under curve, AUC = 0.9668). Analogous results (AUC = 0.9807) were found for the second test collective.
  
  
  CONCLUSIONS
  This novel approach is promising and should be tested on a larger, independent collective.
authors.affiliation: Institute for Prenatal Health, Bahnhofstr. 4, 38300, Wolfenbüttel, Germany. info@dr-schmidt.info
authors.forename: Peter
authors.initials: P
authors.lastname: Schmidt
authors.forename: Cindy
authors.initials: C
authors.lastname: Hörmansdörfer
authors.forename: Bernhard
authors.initials: B
authors.lastname: Vaske
authors.forename: Peter
authors.initials: P
authors.lastname: Hillemanns
authors.forename: Alexander
authors.initials: A
authors.lastname: Scharf
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000782:Aneuploidy; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000235:genetics; D005820:Genetic Testing; D005865:Gestational Age; D006801:Humans; D008403:Mass Screening; D008875:Middle Aged; D008953:Models, Anatomic; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011296:Prenatal Diagnosis; D012372:ROC Curve; D018570:Risk Assessment; D055815:Young Adult
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A