Mutual accreditation study on different methods for glycated hemoglobin measurement with venous and capillary blood samples

Abstract

Objective To compare the differences of different methods for glycated hemoglobin (HbA1c) measurement with venous and capillary blood samples. Methods Total of 91 diabetes outpatients (38 males and 53 females) were selected in Beijing Hospital from January to October 2011. Four fasting venous blood samples were collected in 2 ml EDTA-K2 anti-coagulation vacuum tubes, meanwhile, 32 μl heparin anti-coagulated capillary blood samples were obtained from the ear lobe and the fingertip. These blood samples were immediately measured by G7 in PLA General Hospital, Beijing Hospital and National Center for Clinical Laboratories, or measured by DCA2000+ in community clinics. The blood HbA1c levels were compared among different age groups, different samples on DCA2000+ (from venous, ear lobes, fingertip) or on G7 (from venous and fingertip) and different laboratories and methods. Mann-Whitney test was applied in data comparison between to groups and Kruskal-Wallis test among multiple groups. Results The intra-and inter-assay coefficients of variation(CV) of the DCA2000+ analyzer were all less than 4%, and the intra- and inter-assay CV of the G7 analyzer from 3 hospitals were all 0.05). There was no significant differences in HbA1c levels measured by DCA2000+ with venous, fingertip and ear lobe blood samples in community clinics (χ2=0.474, P>0.05). The results of G7 analysis in Beijing Hospital did not differ significantly with venous blood sample and prediluted fingertip blood(Z=-0.092, P>0.05). There was no statistical differences in HbA1c levels measured in 4 medical institutions using different methods(χ2=5.513, P>0.05). Conclusions Two detecting methods of HbA1c used in the 4 medical facilities have good coherency and repeatability, the results are correlated and can be mutually accredited. The HbA1c levels in venous and capillary blood samples are the same. Key words: Diabetes mellitus; Hemoglobin A, glycated; Clinical laboratory techniques