Commutability and traceability: their repercussions on analytical bias and inaccuracy

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Analytical Science

Background:

• Commutability of calibrators and control materials is crucial for traceability between patient results and standards.
• Non-commutability can impact laboratory practices, including calibration and accuracy assessment.
• Understanding these effects is vital for reliable diagnostic testing.

Purpose of the Study:

• To investigate the impact of commutability on laboratory calibration, bias control, and accuracy assessment.
• To identify solutions for problems caused by non-commutable materials using available resources.
• To evaluate the reliability of commutable materials for assessing analytical error.

Main Methods:

• Studied ten serum constituents, ten comparison procedures, and 37 analytical procedures.
• Challenged accuracy and bias information from commutable materials using native serum results.
• Employed Passing-Bablok regression and decision limits derived from biological variation for method comparison.

Main Results:

• Commutable control materials did not reliably indicate the bias (systematic analytical error) of procedures.
• Results from native serum and commutable controls showed high concordance, suggesting utility for assessing total analytical error.
• Current commutable materials may not fully represent patient samples for bias evaluation.

Conclusions:

• Commutable materials are useful for assessing total analytical error but not systematic bias.
• Native sera with reference method values in External Quality Assessment (EQA) schemes could better evaluate laboratory performance.
• Manufacturers should use reference methods and native sera for calibrator assignment to minimize matrix effects and enhance traceability.