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Discrepancy in HbA1c measurements performed at different local laboratories and at a selected central reference
O N Jensen1, N de Fine Olivarius, P H Petersen
1Department of Clinical Chemistry, Odense University Hospital, Denmark.
Insights
Local HbA1c measurements showed significant bias compared to central labs, impacting patient care. A bias of 0.25% HbA1c is recommended to ensure accurate hemoglobin A1c results.
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- General Practice
Background:
- Glycated hemoglobin (HbA1c) is crucial for diabetes management.
- Variability in HbA1c measurements between local and central laboratories can affect clinical decisions.
- A general practice intervention study highlighted discrepancies in patient HbA1c results.
Purpose of the Study:
- To quantify the bias in HbA1c measurements between local and central laboratories.
- To determine acceptable bias levels for HbA1c testing in clinical practice.
- To describe a control system for HbA1c method standardization and specificity.
Main Methods:
- 66 patients in a general practice study had HbA1c measured locally and at a central reference laboratory.
- Bias was calculated using the mean difference in HbA1c values.
- A control system for method standardization and specificity was developed.
Main Results:
- 97% of local HbA1c results were lower than central laboratory results.
- A mean bias of -1.47% HbA1c was observed between local and central laboratories.
- A bias of 0.5% HbA1c is considered acceptable, with 0.25% HbA1c being the maximum allowed.
Conclusions:
- Significant bias in local HbA1c measurements poses challenges for practitioners, patients, and laboratories.
- Establishing strict bias limits (≤0.25% HbA1c) is essential for reliable diabetes monitoring.
- Implementing a robust control system is vital for standardizing HbA1c methods and ensuring specificity.
Abstract:
As participants in a general practice intervention study, 66 patients had their HbA1c measured both at a local and at a selected central reference laboratory. A discrepancy in the results was observed, as 97% of the results measured locally were lower than the centrally determined results. Bias (as calculated from mean value of measured HbA1c) between local laboratories and the central laboratory was measured to -1.47% HbA1c. A bias of this magnitude gave "problems" both to the general practitioners, patients and laboratories. To reduce the "problems" a bias of 0.5% HbA1c is estimated to be acceptable. But, to avoid these "problems" totally, a bias of 0.25% HbA1c is estimated to be the highest allowed bias. For HbA1c, a control system for both control of method standardisation and for specificity is described.