The application of IFCC reference methods in methodological evaluation of glycated hemoglobin measurement systems

Abstract

Objective To perform a methodological evaluation study of 4 HPLC based systems and a capillary electrophoresis based system, with the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) glycated hemoglobin reference method as a comparative method. Methods 40 hemolysis samples of variety concentrations were prepared. The samples were measured by IFCC reference method and 5 glycated hemoglobin testing systems, respectively and trueness verification was performed according to the Clinical & Laboratory Standards Institute (CLSI) guideline EP9-A3. Whole blood samples were used to test the systems′ precision, linearity and analytical interferences. Results The average CV of IFCC reference method results of 40 hemolysis samples was 1.4%(range from 0.2% to 2.5%). No outlier was found in the results of the 5 testing system. The slopes ranged from 0.990 2 to 1.026 7, and intercepts from -0.152 6 mmol/mol to + 0.151 2 mmol/mol, squared correlation coefficient from 0.996 2-0.997 1, biases at two medical decision level were less than 0.3% HbA1c. Within-laboratory precisions were less than 2% (NGSP unit). Bias between all test results and predicted results were less than 5%. High concentration of glucose showed certain interference to glycated Hemoglobin tests but had little influence in clinical practice. Conclusions The results of the 5 testing system are comparable to the IFCC reference method, the results of precision and linearity evaluation meet the requirements of related guidelines.(Chin J Lab Med, 2018, 41: 821-826) Key words: Hemoglobin A, glycosylated; Reference values; Reference standards; Chromatography, high pressure liquid; Chromatography, ion exchange; Electrophoresis, capillary; Evaluation studies