Evaluation of capillary electrophoresis assay for CDT on SEBIA's Capillarys System: Intra and inter laboratory precision, reference interval and cut-off

• Published in: Clinica chimica acta 2010-12, Vol.411 (23), p.1888-1893
• Main Authors: Schellenberg, François, Wielders, Jos P.M.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Alcohol biomarker; Capillary electrophoresis; CDT; Chromatography, High Pressure Liquid; Clinical Laboratory Techniques; Disialotransferrin; Electrophoresis, Capillary - methods; Electrophoresis, Capillary - standards; Female; Genetic Variation; Humans; Internationality; Linear Models; Male; Middle Aged; Reference Values; Reproducibility of Results; Sensitivity and Specificity; Transferrin - analogs & derivatives; Transferrin - analysis; Transferrin - genetics; Transferrin - isolation & purification; Uncertainty; Young Adult
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2010.07.015

Carbohydrate-deficient transferrin (CDT) measurement on the multicapillary system Capillarys™ is characterized by high throughput and an on-line sample pre-treatment. This study evaluates the linearity and the precision of this technique, the correlation with the candidate reference method and the effect of genetic transferrin variants. Upper reference limit and cut-off values were calculated. The precision study was carried out following CLSI EP5-A protocol. The between laboratory variation was calculated from an eight-site study. The upper reference limit (URL) was conventionally calculated from a reference population of 225 samples and verified by a Bhattacharya analysis in a large (n = 19,129) population. A population of 314 heavy consumers was used for calculation of the cut-off limit. Additionally the measurement uncertainty was calculated according to EDMA (European Diagnostic Manufacturers Association) and IRMM. The imprecision found was less than 5%, linearity was excellent for CDT values ranging from 2% to 20%. The between site variation around the cut-off value (CDT ranging from 1.68% to 1.79%) was clinically not significant. The upper reference limit (95th percentile) was calculated at 1.3% by the conventional IFCC method and confirmed by Bhattacharya calculations. The optimum cut-off for this CZE method was 1.6%, taken into account the measurement uncertainty. The regression equation with the candidate reference method was Disialotransferrin(Capillarys2) = Disialotransferrin(HPLC) ∗ 0.968 − 0.248. Genetic variants and abnormal profiles were well recognized. These results demonstrate that the Capillarys CDT method is robust and reliable in routine use with a high degree of homogeneity from one system to another and is highly correlated with the candidate HPLC reference method.