IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study.
BACKGROUND
The national programs for the harmonization of hemoglobin (Hb)A(1c) measurements in the US [National Glycohemoglobin Standardization Program (NGSP)], Japan [Japanese Diabetes Society (JDS)/Japanese Society of Clinical Chemistry (JSCC)], and Sweden are based on different designated comparison methods (DCMs). The future basis for international standardization will be the reference system developed by the IFCC Working Group on HbA(1c) Standardization. The aim of the present study was to determine the relationships between the IFCC Reference Method (RM) and the DCMs.


METHODS
Four method-comparison studies were performed in 2001-2003. In each study five to eight pooled blood samples were measured by 11 reference laboratories of the IFCC Network of Reference Laboratories, 9 Secondary Reference Laboratories of the NGSP, 3 reference laboratories of the JDS/JSCC program, and a Swedish reference laboratory. Regression equations were determined for the relationship between the IFCC RM and each of the DCMs.


RESULTS
Significant differences were observed between the HbA(1c) results of the IFCC RM and those of the DCMs. Significant differences were also demonstrated between the three DCMs. However, in all cases the relationship of the DCMs with the RM were linear. There were no statistically significant differences between the regression equations calculated for each of the four studies; therefore, the results could be combined. The relationship is described by the following regression equations: NGSP-HbA(1c) = 0.915(IFCC-HbA(1c)) + 2.15% (r(2) = 0.998); JDS/JSCC-HbA(1c) = 0.927(IFCC-HbA(1c)) + 1.73% (r(2) = 0.997); Swedish-HbA(1c) = 0.989(IFCC-HbA(1c)) + 0.88% (r(2) = 0.996).


CONCLUSIONS
There is a firm and reproducible link between the IFCC RM and DCM HbA(1c) values.
Hoelzel
Wieland
W
Roche Diagnostics GmbH, Penzberg, Germany.
Weykamp
Cas
C
Jeppsson
Jan-Olof
JO
Miedema
Kor
K
Barr
John R
JR
Goodall
Ian
I
Hoshino
Tadao
T
John
W Garry
WG
Kobold
Uwe
U
Little
Randie
R
Mosca
Andrea
A
Mauri
Pierluigi
P
Paroni
Rita
R
Susanto
Fransiscus
F
Takei
Izumu
I
Thienpont
Linda
L
Umemoto
Masao
M
Wiedmeyer
Hsiao-Mei
HM
D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards; D002138:Calibration; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000592:standards; D006801:Humans; D007564:Japan; D009313:National Health Programs; D012015:Reference Standards; D013548:Sweden; D014481:United States
D006442:Glycated Hemoglobin