title: Should cell-free fetal DNA be included in first trimester screening (FTS) for common trisomy? A possible scenario on 6697 women screened over 10 years.
abstract: OBJECTIVE
  The primary aim was to determine the performance of the first trimester screening (FTS) test in a general obstetrics population. Cost-benefit analysis of a hypothetic model based on implementation of the FTS test by cell-free fetal (cff) DNA was calculated.
  
  
  METHODS
  A total of 6697 women were screened using FTS test. A two-step strategy based upon nuchal translucency, serum screening and ultrasound assessment of nasal bone (NB) was applied. Three groups were identified (high-risk: >1:250; intermediate-risk: 1:251-1:999 and low-risk group: <1:1000). Women at intermediate-risk (1:251-1:999) underwent NB assessment and recalculation of individual risk. All women at high-risk were offered fetal karyotyping.
  
  
  RESULTS
  A total of 321 women (4.8%) resulted at high-risk while 480 women (7.1%) with intermediate-risk underwent assessment of the NB, which was absent in 15 fetuses. Overall, 54 aneuploidies were detected for a 96.4% sensitivity, a 96.1% specificity, a 99.9% negative predictive value and a false positive rate of 4.8%. Audit was conducted on a yearly basis and lost to follow up was 0.47% (32 cases).
  
  
  CONCLUSIONS
  Public health system would not be able to cover the cost of including cff DNA in women undergoing first trimester screening on universal basis. However, assuming a possible scenario based on implementation of FTS by cff DNA in women at high-risk would result in a 6-fold reduction in the number of invasive procedures while avoiding two false negative results (trisomy 21) that were diagnosed in women with intermediate-risk using current screening strategy by combined test.
authors.affiliation: Center for Prevention of Fetal Malformations, Department of Obstetrics and Gynecology, Hospital Meyer, Florence, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Rosignoli
authors.affiliation: Prenatal Diagnostic Center, Department of Obstetrics and Gynecology, Guastalla Civil Hospital, AUSL Reggio Emilia, Reggio Emilia, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Tonni
mesh_terms: D000328:Adult; D003362:Cost-Benefit Analysis; D004247:DNA / Q000097:blood*; D005260:Female; D006291:Health Policy; D006801:Humans; D062145:Maternal Serum Screening Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*; D011634:Public Health; D012189:Retrospective Studies; D014314:Trisomy / Q000175:diagnosis*; D016216:Ultrasonography, Prenatal
chemical_list: D004247:DNA
keywords: diagnosis; health policy; public health