title: Rapid testing versus karyotyping in Down's syndrome screening: cost-effectiveness and detection of clinically significant chromosome abnormalities.
abstract: In all, 80% of antenatal karyotypes are generated by Down's syndrome screening programmes (DSSP). After a positive screening, women are offered prenatal foetus karyotyping, the gold standard. Reliable molecular methods for rapid aneuploidy diagnosis (RAD: fluorescence in situ hybridization (FISH) and quantitative fluorescence PCR (QF-PCR)) can detect common aneuploidies, and are faster and less expensive than karyotyping.In the UK, RAD is recommended as a standalone approach in DSSP, whereas the US guidelines recommend that RAD be followed up by karyotyping. A cost-effectiveness (CE) analysis of RAD in various DSSP is lacking. There is a debate over the significance of chromosome abnormalities (CA) detected with karyotyping but not using RAD. Our objectives were to compare the CE of RAD versus karyotyping, to evaluate the clinically significant missed CA and to determine the impact of detecting the missed CA. We performed computer simulations to compare six screening options followed by FISH, PCR or karyotyping using a population of 110948 pregnancies. Among the safer screening strategies, the most cost-effective strategy was contingent screening with QF-PCR (CE ratio of $24084 per Down's syndrome (DS) detected). Using karyotyping, the CE ratio increased to $27898. QF-PCR missed only six clinically significant CA of which only one was expected to confer a high risk of an abnormal outcome. The incremental CE ratio (ICER) to find the CA missed by RAD was $66608 per CA. These costs are much higher than those involved for detecting DS cases. As the DSSP are mainly designed for DS detection, it may be relevant to question the additional costs of karyotyping.
authors.affiliation: Centre de Recherche du CHUQ, Service de Génétique Médicale, Unité de Diagnostic Prénatal, Département de Pédiatrie, Université Laval, Québec City, Québec, Canada. jean.gekas@mail.chuq.qc.ca
authors.forename: Jean
authors.initials: J
authors.lastname: Gekas
authors.forename: David-Gradus
authors.initials: DG
authors.lastname: van den Berg
authors.forename: Audrey
authors.initials: A
authors.lastname: Durand
authors.forename: Maud
authors.initials: M
authors.lastname: Vallée
authors.forename: Hajo Izaäk Johannes
authors.initials: HI
authors.lastname: Wildschut
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bujold
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Forest
authors.forename: François
authors.initials: F
authors.lastname: Rousseau
authors.forename: Daniel
authors.initials: D
authors.lastname: Reinharz
mesh_terms: D000328:Adult; D002869:Chromosome Aberrations; D003362:Cost-Benefit Analysis; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D005820:Genetic Testing / Q000191:economics* / Q000379:methods; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000191:economics; D007231:Infant, Newborn; D007621:Karyotyping / Q000379:methods*; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000191:economics; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000191:economics* / Q000379:methods; D013997:Time Factors; D055815:Young Adult