Comparative Analytical Performance of Various HbA1c Assays in Iran.

INTRODUCTION: Hemoglobin A1c (HbA1c) measurement devices are widely used to evaluate glycemic control in diabetic patients. The aim of this study was to investigate the comparability of various HbA1c instruments used in Iran. METHODS: In the present study, 154 fresh whole blood samples from diabetic patients, with different HbA1c levels (4.0%-10%) and no types of hemoglobinopathy were analyzed by six HbA1c assays including one high performance liquid chromatography (HPLC) method (D10 HbA1c), two immunoassay methods (COBAS INTEGRA 400 and Pars Azmoon kit), one Boronate affinity method (Nycocard Reader II), and two ion exchange methods (Biosystems and DS5). The two National Glycohemoglobin Standardization Programs (NGSP) certified system, D10 and COBAS INTEGRA 400 which are certified as secondary reference measurement procedures, were considered as reference methods. The CLSI document (EP9-A2) - Method comparison and Bias estimation using patient samples, approved guideline - was used to compare the performance of different HbA1c instruments. RESULTS: The mean of HbA1c in all four types of assays was less than the reference methods (P-value < 0.01).The mean of absolute difference between the reference methods was the least (0.11%). Among the other four tests, Biosystems had the smallest mean of difference (-0.21%), while Pars Azmoon had the highest (-1.18%). Pars Azmoon showed the greatest difference (95% confidence interval) when compared to D10 [-15.5%(-5.7%to -25.3%)] and COBAS INTEGRA [-17% (-9.16% to -24.84%)]. The highest regression slope (B) was found in DS5 method (0.96) in regression model with both reference methods. CONCLUSION: It can be concluded that although HbA1c standardization programs have resulted in great improvements in the comparability of HbA1c assays, unacceptable errors still exist and further national and international projects are required for standardization of HbA1c measurement. In this situation, it is recommended to use the same laboratory for HbA1c measurement to monitor diabetic patients.

Comparability of hemoglobin A1c level measured in capillary versus venous blood sample applying two point-of-care instruments.

BACKGROUND: The present study is designed to evaluate the validity of the measurement of capillary blood hemoglobin A1c levels in comparison with venous blood hemoglobin A1c. METHODS: The data of this cross-sectional study are collected from a sample of 45 Iranian diabetic patients referred to one particular laboratory for the assessment of HbA1c level during a period from April to December 2013. Venous and simultaneous capillary blood samples were obtained from each subject for measurement of hemoglobin A1c levels. Both samples were tested using two different NGSP certified systems: CERA STAT 2000 (Ceragem Medisys Inc) and NycoCard Reader II (Axis-Shield). RESULTS: The mean hemoglobin A1c in venous and capillary blood samples measured using CERA STAT 2000 assays were 6.30 ± 1.68% and 6.34 ± 1.65% respectively (p = 0.590). However, when NycoCard Reader II assay was employed, the mean hemoglobin A1c in venous and capillary blood samples were 6.73 ± 1.35% and 6.92 ± 1.50% (p = 0.007). Moreover, a strong correlation was observed between venous and capillary hemoglobin A1c levels with Pearson's concordance correlation coefficients of 0.96 and 0.94 with the use of NycoCard Reader II and CERA STAT 2000 assays respectively. Application of CERA STAT 2000 demonstrated to be of a considerably higher value using the ROC curve analysis assay (AUC = 0.991). Also, similar analysis by using NycoCard Reader II assay demonstrated that capillary hemoglobin A1c measurement had high value for differentiation of uncontrolled from controlled blood glucose level (AUC = 0.935). CONCLUSION: It was demonstrated that capillary hemoglobin A1c measurement had a considerably high value for differentiating between poorly-controlled and well-controlled blood glucose levels.