The IFCC Reference Measurement System for HbA1c: a 6-year progress report.

Area of Science:

• Clinical Chemistry
• Metrology
• Diabetes Mellitus Diagnostics

Background:

• The IFCC Reference Measurement System for hemoglobin A1c (HbA1c) is established with metrologic traceability.
• A network of 14 international reference laboratories supports the IFCC-RM.
• This study reports on 12 intercomparison studies assessing the IFCC-RM's performance.

Purpose of the Study:

• To evaluate the performance and stability of the IFCC Reference Measurement System for HbA1c.
• To assess the long-term continuity and reliability of HbA1c measurements.
• To compare the IFCC-RM with designated comparison methods (DCMs).

Main Methods:

• Utilized unknown and known samples, calibrators, and calibration sets for intercomparison studies.
• Measured unknown samples using the IFCC-RM and compared with DCMs (NGSP, JDS/JSCC, Mono-S).
• Investigated the stability of the Master Equation (ME) relating IFCC-RM and DCMs.

Main Results:

• 95 out of 105 IFCC-RM data sets were approved, indicating overall system validity.
• Trend analysis of MEs showed minimal, non-significant changes for NGSP and Mono-S, but a significant change for JDS/JSCC.
• Long-term performance showed no systematic change; mass spectrometry and capillary electrophoresis yielded comparable mean HbA1c, with CE showing better reproducibility. One calibrator batch was unapproved, but stored calibrators were stable.

Conclusions:

• The IFCC Reference Measurement System for HbA1c is sound, ensuring continuity and stability.
• The system provides a reliable analytical anchor for HbA1c measurements.
• Ongoing intercomparison studies are essential for maintaining the integrity of the IFCC-RM.