Specimen materials, target values and commutability for external quality assessment (proficiency testing) schemes

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Quality Assurance

Background:

• External quality assessment (EQA) is crucial for evaluating the clinical acceptability of laboratory results.
• Intermethod harmonization and traceability to a reference system are key goals for EQA programs.

Purpose of the Study:

• To assess the suitability of different materials for EQA.
• To evaluate methods for assessing intermethod harmonization and traceability.

Main Methods:

• Conventional EQA utilizes stable, matrix-modified processed materials, but they lack commutability.
• Authentic clinical specimen pools offer commutability but have limited availability and analyte range.
• Hybrid approaches combine processed materials and clinical specimens to derive target values for traceability evaluation.

Main Results:

• Non-commutability of processed materials limits their use for traceability and harmonization assessment.
• Limited availability of pooled clinical specimens restricts their comprehensive use.
• Hybrid approaches enable the evaluation of traceability to reference methods.

Conclusions:

• Conventional processed materials are limited by non-commutability, hindering traceability and harmonization evaluation.
• Pooled clinical specimens are limited by availability.
• Combining processed materials and pooled clinical specimens in EQA effectively evaluates traceability and harmonization.