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Practice Guideline
. 2018 Mar;64(3):455-464.
doi: 10.1373/clinchem.2017.277541. Epub 2018 Jan 18.

IFCC Working Group Recommendations for Assessing Commutability Part 2: Using the Difference in Bias between a Reference Material and Clinical Samples

Göran Nilsson  1 , Jeffrey R Budd  2 , Neil Greenberg  3 , Vincent Delatour  4 , Robert Rej  5 , Mauro Panteghini  6 , Ferruccio Ceriotti  7 , Heinz Schimmel  8 , Cas Weykamp  9 , Thomas Keller  10 , Johanna E Camara  11 , Chris Burns  12 , Hubert W Vesper  13 , Finlay MacKenzie  14 , W Greg Miller  15 ; IFCC Working Group on Commutability
Affiliations
Practice Guideline

IFCC Working Group Recommendations for Assessing Commutability Part 2: Using the Difference in Bias between a Reference Material and Clinical Samples

Göran Nilsson et al. Clin Chem. 2018 Mar.

Abstract

A process is described to assess the commutability of a reference material (RM) intended for use as a calibrator, trueness control, or external quality assessment sample based on the difference in bias between an RM and clinical samples (CSs) measured using 2 different measurement procedures (MPs). This difference in bias is compared with a criterion based on a medically relevant difference between an RM and CS results to make a conclusion regarding commutability. When more than 2 MPs are included, the commutability is assessed pairwise for all combinations of 2 MPs. This approach allows the same criterion to be used for all combinations of MPs included in the assessment. The assessment is based on an error model that allows estimation of various random and systematic sources of error, including those from sample-specific effects of interfering substances. An advantage of this approach is that the difference in bias between an RM and the average bias of CSs at the concentration (i.e., amount of substance present or quantity value) of the RM is determined and its uncertainty estimated. An RM is considered fit for purpose for those MPs for which commutability is demonstrated.

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Conflict of interest statement

Authors’ Disclosures or Potential Conflicts of Interest: Upon manuscript submission, all authors completed the author disclosure form. Disclosures and/or potential conflicts of interest:

Employment or Leadership: R. Rej, Clinical Chemistry, AACC; C.J. Burns, National Institute for Biological Standards and Control; W.G. Miller, Clinical Chemistry, AACC.

Consultant or Advisory Role: None declared.

Stock Ownership: None declared.

Honoraria: None declared.

Research Funding: None declared.

Expert Testimony: None declared.

Patents: None declared.

Other Remuneration: N. Greenberg, College of American Pathologists.

Figures

Fig. 1
Fig. 1. Precision profiles as SD vs concentration
(A) shows an approximately constant SD over the concentration interval. (B) shows a proportional relationship between SD and concentration.
Fig. 2
Fig. 2. Difference in concentration (A) and ln(concentration) (B) for the same data vs mean concentration of both MPs
(A) is from spreadsheet tab CS_Trans found in the online Data Supplement. (B) is from spreadsheet tab CS_Trans (2) found in the online Data Supplement.
Fig. 3
Fig. 3. Difference in bias between RMs (red squares) and CSs (black diamonds) vs mean concentration of the 2 measuring systems
The solid black line is the mean bias between the 2 measurement procedures for the CSs. The red dashed lines are the commutability criteria. The red squares are the mean bias between the 2 MPs for the RMs, and the bars are the uncertainty in the difference in bias between RM and CS mean bias. RM1, RM2, and RM4 are indeterminate; RM3 is commutable; RM5 is noncommutable. Fig. 3 is from the spreadsheet tab CS&RM_Diff found in the online Data Supplement.
Fig. 4
Fig. 4. Summary of commutability conclusions for a RM for multiple MPs
(A) shows a representation of commutability conclusions for all combinations of pairs of MPs. (B) shows a representation when an RMP is available. The notation C, I, N could be replaced with numeric values for difference in bias and its uncertainty if desired.
See this image and copyright information in PMC

Comment in

References

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