Evaluation of the analytical performance of Roche immunoturbidimetric immunoglobulin assays and comparing to Dade Behring immunonephelometer

Abstract

Objective: The aim of this study is to evaluate the analytical performance of the Roche immunoturbidimetric immunoglubulin assays, and also compare the results obtained by Roche immunoturbidimetric method to Dade Behring II Nephelometer. Methods: Low and high concentration patient samples and internal quality control materials were used to evaluate precision, limit of detection (LoD) linearity, and sample carry over of Roche immunoturbidimetric analyzer. External quality control results were used to evaluate accuracy. For method comparison, 451 patients serum were analyzed using Roche Hitachi Modular P System with an immunoturbidimetric method and Dade Behring BNII immunonephelometer with an immunonephelometric method. Results: In precision study on Roche immunoturbidimetric immunoglobulin assays, imprecision values were 1.37%, 3.88% and 5.34% for IgG, A and M, respectively. Correlation coefficents between Roche immunoturbidimetric analysis and Dade Behring BN II immunonephelometer were 0.967, 0.979 and 0.939 for IgG, IgA and IgM respectively. Conclusion: In immunoturbidimetric Roche Ig analyses precision for IgG was allowable according to the the desirable quality specifications. However, both IgA and IgM had higher imprecisions than the desirable total precision. Immunoturbidimetric Roche Ig analyses were found linear in the reference values but unreliable results were observed in the presence of excess antigen. The same samples performed on Roche analyzers needed to be diluted suggesting Dade Behring had wider linearity range than Roche immunoturbidimetric analyzer in the presence of excess antigen