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Suitability of reference materials for reliable clinical measurement results

May 08 2018

New concepts and guidance for assessing the commutability of reference materials for the use as calibrators in clinical measurements were developed by a working group of the International Federation of Clinical Chemists (IFCC) with contribution of the JRC. The work is relevant for the JRC as it develops and provides a number of clinical reference materials. 

For testing of clinical samples, it is important to have close agreement between results using different measurement procedures in order to make the appropriate diagnosis and medical decision. Suitable reference materials (RMs) for calibration are crucial for making clinical results (e.g. in vitro diagnostic tests) comparable.

Only if commutable reference materials are used as common calibrators for in vitro diagnostic tests (IVDs), harmonisation or standardisation of results from different IVDs can be achieved. The use of non-commutable reference materials would create a bias in IVD results or would lead to invalid conclusions if used for performance assessment. Commutability of RMs and calibrators is a common issue in laboratory medicine. Hence commutability is an important property of reference materials in a clinical diagnostic and regulatory context. 

The understanding and assessment of commutability is technically demanding. Commutability is a reference material property which is indicated by a close correlation between measurement results of different IVDs for reference materials and for those samples, which are typically analysed in a routine context and for which the various IVDs have been designed and optimised for.

Therefore, the IFCC working group on commutability developed new concepts and guidance for assessing the commutability of RMs which were laid out in a series of initially 3 publications. 

  • The first manuscript focuses on the conditions under which the assessment of commutability is meaningful, on conceptual aspects and experimental design of commutability assessment studies. 
  • The second manuscript describes the mathematical models which could be used to assess commutability of a reference material before it is being used for calibration of IVDs. 
  • The third manuscript describes a way to validate commutability of a reference material by assessing the equivalence of results of IVDs for which the reference material has been used as a common calibrator. 

These new concepts will be taken into account for the development and processing of new clinical RMs by the JRC being a recognised RM producer.

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