Evaluation of the analytical performance of two vitamin D immunoassay methods

INTRODUCTION: The increasing clinical significance of 25-hydroxyvitamin D [25(OH)D] has made it an indispensable test in the laboratory. The aim of this study was to investigate the analytical performance of 2 widely used immunoassay methods, the new Abbott Architect 5P02 25-OH Vitamin D assay (Abbott Laboratories, Lake Bluff, IL, USA) and the Beckman Coulter product, the Access 25 (OH) Vitamin D Total assay (Beckman Coulter, Inc., Brea, CA, USA).
METHODS: A total of 96 serum samples were used to compare the accuracy, linearity, limit of blank, limit of detection, limit of quantification, and precision of the 2 tests using the Architect i2000SR System (Abbott Laboratories, Lake Bluff, IL, USA) and the Access2 (Beckman Coulter, Brea, CA, USA) immunoassay platform. Deming regression analysis and Bland Altman graphs were used to compare the 2 methods.
RESULTS: The within-run coefficient of variation (CV%) of the Architect and the Access systems was <3.1% and <6.72%, respectively. There was good linearity of the 25(OH)D measurement at 98.9-114% for the Architect assay and 94.1-103.5% for the Access assay at concentrations of 5-160 ng/mL and 6.2-210.4 ng/mL, respectively. The correlation coefficient was 0.921 (y=-2.1+0.97x).
DISCUSSION AND CONCLUSION: Thorough testing indicated that the new 5P02 Abbott Architect 25(OH)D and the Beckman Coulter Access2 25(OH)D Total test demonstrated appropriate analytical performance.