title: Performance of free beta-human chorionic gonadotrophin (free beta-hCG) and pregnancy associated plasma protein-A (PAPP-A) analysis between Delfia Xpress and AutoDelfia systems in The Netherlands.
abstract: BACKGROUND
  The VU University Medical Center (VUmc) was the first hospital in the Netherlands to introduce the Delfia Xpress for the analysis of free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy associated plasma protein-A (PAPP-A) in the first trimester screening program for Down syndrome. Since then, others have implemented this system. In this study, we tested the equality of measurements for free beta-hCG and PAPP-A between Delfia Xpress systems and one AutoDelfia system.
  
  
  METHODS
  A total of 40 serum samples were aliquoted and stored at -20 degrees C. Samples were analyzed by six Delfia Xpress systems and one AutoDelfia system over a time period of 2 years.
  
  
  RESULTS
  The relationships between free beta-hCG and PAPP-A were excellent for the different Delfia Xpress systems (r>0.99, p<0.0001). For PAPP-A, the agreement between the main system at VUmc and five other systems was linear with slopes between 0.99 and 1.06. Similarly, agreement for free beta-hCG was linear with slopes between 0.99 and 1.09. Likewise, agreement for PAPP-A and free beta-hCG was excellent for the AutoDelfia vs. the main Delfia Xpress at the VUmc (r>0.99, p<0.0001). For both PAPP-A and free beta-hCG, the relationships were linear with slopes of 1.08 and 1.07.
  
  
  CONCLUSIONS
  We demonstrate an excellent agreement for the analysis of PAPP-A and free beta-hCG between Delfia Xpress systems and one AutoDelfia system.
authors.affiliation: Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Ingeborg H
authors.initials: IH
authors.lastname: Linskens
authors.forename: Marieke
authors.initials: M
authors.lastname: Levitus
authors.forename: Anneke
authors.initials: A
authors.lastname: Frans
authors.forename: Peter C J I
authors.initials: PC
authors.lastname: Schielen
authors.forename: John M G
authors.initials: JM
authors.lastname: van Vugt
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Blankenstein
authors.forename: Hilde M
authors.initials: HM
authors.lastname: Dijstelbloem
mesh_terms: D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D009426:Netherlands; D011237:Predictive Value of Tests; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011933:Reagent Kits, Diagnostic; D011266:Pregnancy-Associated Plasma Protein-A