Performance of free β-human chorionic gonadotrophin (free β-hCG) and pregnancy associated plasma protein-A (PAPP-A) analysis between Delfia Xpress and AutoDelfia systems in The Netherlands

• Published in: Clinical chemistry and laboratory medicine Vol. 47; no. 2; pp. 222 - 226
• Main Authors: Linskens, Ingeborg H., Levitus, Marieke, Frans, Anneke, Schielen, Peter C.J.I., van Vugt, John M.G., Blankenstein, Marinus A., Dijstelbloem, Hilde M.
• Format: Journal Article
• Language: English
• Published: Germany Walter de Gruyter 01.02.2009
• Subjects: AutoDelfia; Chorionic Gonadotropin, beta Subunit, Human - blood; Delfia Xpress; Down Syndrome - blood; Down Syndrome - diagnosis; first trimester Down syndrome screening; free β-human chorionic gonadotrophin; Humans; Immunoassay - instrumentation; Immunoassay - methods; Netherlands; Predictive Value of Tests; pregnancy associated plasma protein-A; Pregnancy-Associated Plasma Protein-A - analysis; Reagent Kits, Diagnostic; Reproducibility of Results; Sensitivity and Specificity; Netherlands
• ISSN: 1434-6621; 1437-4331
• DOI: 10.1515/CCLM.2009.042

Background: The VU University Medical Center (VUmc) was the first hospital in the Netherlands to introduce the Delfia Xpress for the analysis of free β-human chorionic gonadotrophin (β-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 β-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°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 β-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 β-hCG was linear with slopes between 0.99 and 1.09. Likewise, agreement for PAPP-A and free β-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 β-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 β-hCG between Delfia Xpress systems and one AutoDelfia system. Clin Chem Lab Med 2009;47:222–6.