title: 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.
abstract: 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.
authors.affiliation: Roche Diagnostics GmbH, Penzberg, Germany.
authors.forename: Wieland
authors.initials: W
authors.lastname: Hoelzel
authors.forename: Cas
authors.initials: C
authors.lastname: Weykamp
authors.forename: Jan-Olof
authors.initials: JO
authors.lastname: Jeppsson
authors.forename: Kor
authors.initials: K
authors.lastname: Miedema
authors.forename: John R
authors.initials: JR
authors.lastname: Barr
authors.forename: Ian
authors.initials: I
authors.lastname: Goodall
authors.forename: Tadao
authors.initials: T
authors.lastname: Hoshino
authors.forename: W Garry
authors.initials: WG
authors.lastname: John
authors.forename: Uwe
authors.initials: U
authors.lastname: Kobold
authors.forename: Randie
authors.initials: R
authors.lastname: Little
authors.forename: Andrea
authors.initials: A
authors.lastname: Mosca
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Mauri
authors.forename: Rita
authors.initials: R
authors.lastname: Paroni
authors.forename: Fransiscus
authors.initials: F
authors.lastname: Susanto
authors.forename: Izumu
authors.initials: I
authors.lastname: Takei
authors.forename: Linda
authors.initials: L
authors.lastname: Thienpont
authors.forename: Masao
authors.initials: M
authors.lastname: Umemoto
authors.forename: Hsiao-Mei
authors.initials: HM
authors.lastname: Wiedmeyer
mesh_terms: 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
chemical_list: D006442:Glycated Hemoglobin