Comparative Analytical Performance of Various HbA1c Assays in Iran.
BACKGROUND
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.


CONCLUSIONS
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.
Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
Farideh
F
Razi
Reference Health Laboratory of Iran, Ministry of Health, Tehran, Iran.
Marjan
M
Rahnamaye Farzami
Massoud Clinical Laboratory, Tehran, Iran.
Soltan Ahmad
SA
Ebrahimi
Massoud Clinical Laboratory, Tehran, Iran.
Mehrzad
M
Nahid
Massoud Clinical Laboratory, Tehran, Iran.
Mostafa Gholi
MG
Bigdeli
4)Department of Biostatistics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 5)Non-Communicable Disease Research Center, Endocrinology and Metabolism Population Science Institute, Tehran University of Medical Sciences, Tehran, Iran.
Ali
A
Sheidaei
Non-Communicable Disease Research Center, Endocrinology and Metabolism Population Science Institute, Tehran University of Medical Sciences, Tehran, Iran.
Anoosheh
A
Ghasemian
Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
Ali
A
Tootee
Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
Tahereh
T
Keramati
Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
Ensieh
E
Nasli Esfahani
Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
Bagher
B
Larijani
Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Parvin
P
Pasalar
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003920:Diabetes Mellitus / Q000097:blood*; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007492:Iran; D016014:Linear Models; D012015:Reference Standards; D015203:Reproducibility of Results
D006442:Glycated Hemoglobin