Trueness in the measurement of haemoglobin: consensus or reference method?

Area of Science:

• Clinical chemistry
• Laboratory diagnostics
• Haematology

Background:

• A reference method for haemoglobin measurement, the haemiglobincyanide method, is available.
• A Dutch external quality assessment organization does not utilize this reference method for evaluating result trueness.
• This study investigates potential compromises in trueness due to the use of consensus values.

Purpose of the Study:

• To assess the trueness of haemoglobin measurements using Cell Dyn Sapphires.
• To compare the accuracy of Cell Dyn Sapphire results against the haemiglobincyanide reference method.
• To evaluate the reliability of consensus values from external quality assessment in determining haemoglobin measurement accuracy.

Main Methods:

• Haemoglobin concentration was measured on five Cell Dyn Sapphires across three locations.
• Results were compared to the established haemiglobincyanide reference method.
• Systematic deviations were analyzed using Passing and Bablok regression and Bland-Altman plots with patient and external quality assessment samples.

Main Results:

• Cell Dyn Sapphire haemoglobin measurements showed significant deviation from the reference method.
• Consensus results from external quality control samples also exhibited significant deviation from the reference method.
• A notable negative bias was observed in both the instrument measurements and the consensus values.

Conclusions:

• Cell Dyn Sapphires demonstrate a significant negative bias in haemoglobin measurement.
• External quality assessment consensus values display a greater negative bias compared to the reference method.
• External quality assessment should adopt the haemiglobincyanide reference method for improved trueness evaluation.