Performance of glycated hemoglobin (HbA(1c)) methods evaluated with EQAS studies using fresh blood samples: Still...

The determination of glycated hemoglobin is a key indicator for the management of diabetic patients. A reference measurement system for its determination is available and IVD manufacturers should have aligned their assay to this system.

Two fresh blood samples were distributed by courier to 206 Italian laboratories asking for the determination of their HbA1c concentration. Target HbA1c values were assigned by the IFCC reference measurement procedure.

From 193 laboratories using analytical systems from five manufacturers (Bio-Rad Laboratories, A. Menarini Diagnostics, Roche Diagnostics, Sebia and Tosoh), we obtained a global variability of 5.3% (in terms of CV) and of 3.8% at an HbA1c value of 37.4 mmol/mol (sample 1) and 62.0 mmol/mol (sample 2), respectively. With a goal for the allowable total error (TE) of 6.0%, 70% and 77% of the participants met this criterion for samples 1 and 2, respectively. Inter-laboratory CVs, were between 3.3 and 5.0% and between 2.2 and 3.7% for samples 1 and 2, respectively. Tosoh users registered the smallest inter-laboratory CV in sample 1, and Sebia's in sample 2. With regard to trueness, all methods had a mean bias of ≤ 2.8% with respect to the target values, with the exception of Tosoh (bias of + 6.1 and + 5.8%, for samples 1 and 2, respectively).

These results are in good agreement with those obtained by the CAP 2014 GH2-A survey, suggesting then that still there is an urgent need for improving a significant part of the methods currently used to measure HbA1c.