IFCC Working Group Recommendations for Assessing Commutability Part 2: Using the Difference in Bias between a...

Area of Science:

• Clinical Chemistry
• Biomedical Engineering
• Laboratory Medicine

Background:

• Commutability of reference materials (RMs) is crucial for accurate laboratory diagnostics.
• Current methods for assessing commutability can be complex and vary across measurement procedures (MPs).
• Ensuring RMs perform consistently across different analytical methods is essential for reliable patient results.

Purpose of the Study:

• To describe a novel process for evaluating the commutability of reference materials (RMs).
• To establish a standardized method for assessing RM suitability as calibrators, trueness controls, or external quality assessment samples.
• To provide a robust framework for comparing RM performance against clinical samples (CSs) across multiple measurement procedures.

Main Methods:

• The process assesses commutability by analyzing the difference in bias between RMs and CSs using two or more MPs.
• A criterion based on medically relevant differences is used to conclude commutability.
• An error model is employed to estimate random and systematic error sources, including sample-specific interfering effects.

Main Results:

• The method quanties the difference in bias between an RM and the average bias of CSs at the RM's concentration.
• Uncertainty estimation for the bias difference is incorporated into the assessment.
• Commutability is demonstrated when the bias difference falls within the defined criterion for specific MPs.

Conclusions:

• The described process offers a reliable method for assessing RM commutability across diverse measurement procedures.
• This approach ensures RMs are fit for purpose, enhancing the accuracy and comparability of laboratory test results.
• The method accounts for complex error sources, improving the overall validity of reference material assessments.