The Clinical and Laboratory Standards Institute (CLSI) has published an updated standard—Evaluation of Commutability of Processed Samples; Approved Guideline—Third Edition (EP14-A3)—which provides guidance for evaluating the commutability of processed samples by determining if they behave differently than unprocessed patient samples when two quantitative measurement procedures are compared.

This edition of the standard provides ways to identify the presence of noncommutability so that improvements in measurement procedure specificity and fluid compatibility may be considered. It also covers risk of noncommutability of processed samples versus intended use.

“This third edition of EP14-A3 balances a more rigorous Deming regression analysis with manageable sample sizes and helpful detailed example calculations. Users will find that the contributors to the document appreciate that not all processed sample types should be considered the same with respect to the relative risk of noncommutability to the quality of patient care,” highlighted EP14-A3 Document Development Committee Chairholder, Karl De Vore, Principal R&D Scientist, Bio-Rad Laboratories, Irvine, California, USA.

This EP14 revision contains a number of modifications intended to improve the science of the evaluation process for matrix effects as well as provide guidance as to when it should be used. EP14-A3 includes detailed examples that help manufacturers develop and check their calculations during initial implementation of the protocol.

The document is intended to be used by developers of commercial diagnostic tests as well as laboratory-developed tests, manufacturers of measuring interval sample sets and quality control samples, and proficiency testing or external quality assessment providers. This guideline may also be useful to all clinical laboratory professionals wishing to investigate a processed sample’s commutability.

CLSI is a not-for-profit membership organization that brings together the varied perspectives and expertise of the worldwide laboratory community for the advancement of a common cause: to foster excellence in laboratory medicine by developing and implementing clinical laboratory standards and guidelines that help laboratories fulfill their responsibilities with efficiency, effectiveness, and global applicability.

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