title: Noninvasive prenatal testing in the general obstetric population: clinical performance and counseling considerations in over 85 000 cases.
abstract: OBJECTIVE
  The primary goal of this study was to provide clinically relevant information for appropriate patient counseling.
  
  
  METHODS
  Demographics and test metrics were reviewed for 86 658 clinical cases. Outcome information was requested for samples reported as aneuploidy detected or suspected for chromosomes 21, 18, or 13; voluntary outcome reporting was encouraged for all discordant outcomes.
  
  
  RESULTS
  Of 86 658 cases, 85 298 (98.4%) met inclusion criteria for result reporting. Of the 1360 (1.6%) cancellations, only 101 (0.1%) were for technical reasons. Average time to result was 3.3 business days. Aneuploidy was detected or suspected in 2142 (2.5%) samples. For aneuploidy detected cases with known clinical outcomes, the overall positive predictive value (PPV) was 83.5% (608/728); observed PPVs for trisomies 21, 18, and 13 ranged from 50.0 to 92.8%. As individual PPVs are determined by a patient's prior risk, we developed a chart for counseling patients on positive predictive value based on maternal age.
  
  
  CONCLUSIONS
  This large-scale report reinforces that noninvasive prenatal testing is a highly accurate screen for fetal aneuploidy in the general obstetric population. Test improvements have facilitated a reduction in failure rates, time to result, and borderline results/unclassifiable results. We have developed a positive predictive value counseling tool to ensure appropriate patient education, counseling, and clinical utilization.
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Taneja
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Holly L
authors.initials: HL
authors.lastname: Snyder
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Eileen
authors.initials: E
authors.lastname: de Feo
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Kruglyak
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Meredith
authors.initials: M
authors.lastname: Halks-Miller
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Kirsten J
authors.initials: KJ
authors.lastname: Curnow
authors.affiliation: Illumina, Redwood City, CA, USA.
authors.forename: Sucheta
authors.initials: S
authors.lastname: Bhatt
mesh_terms: D000293:Adolescent; D000328:Adult; D000782:Aneuploidy; D003376:Counseling / Q000592:standards / Q000706:statistics & numerical data*; D005260:Female; D005820:Genetic Testing / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D008875:Middle Aged; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011296:Prenatal Diagnosis / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D055815:Young Adult