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.

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.