Multicenter Evaluation of a Commercial Cytomegalovirus Quantitative Standard: Effects of Commutability on Interlaboratory Concordance

Hayden, Randall T.; Shahbazian, M. D.; Valsamakis, Alexandra; Boonyaratanakornkit, Jerry; Cook, Linda; Pang, Xiaomin; Preiksaitis, Jutta K.; Schönbrunner, E. Ralf; Caliendo, Angela M.

doi:10.1128/jcm.02036-13

Cited by 34 publications

(21 citation statements)

References 14 publications

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“…This has primarily been demonstrated on a smaller scale, with just a few assays. In the latter case, implementation of common, commercially produced standards could only improve agreement among labs when commutable and actually could reduce agreement when noncommutable (17). Other factors may come into play as well.…”

Section: Discussionmentioning

confidence: 99%

“…Commutability of reference material is critical to producing quantitative values reflective of reality in vivo and is a necessary ingredient if such material is to reduce variability among laboratories. In fact, commutable quantitative standards have been shown to improve interlaboratory agreement, while noncommutable standards have actually been shown to increase disparity among testing centers (17). Here we examine the commutability of the first WHO International Standard (WHO IS) for HCMV (09/162), among a wide variety of commonly used CMV quantitative assays.…”

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confidence: 99%

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Commutability of the First World Health Organization International Standard for Human Cytomegalovirus

et al. 2015

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Quantitative detection of cytomegalovirus (CMV) DNA has become a standard part of care for many groups of immunocompromised patients; recent development of the first WHO international standard for human CMV DNA has raised hopes of reducing interlaboratory variability of results. Commutability of reference material has been shown to be necessary if such material is to reduce variability among laboratories. Here we evaluated the commutability of the WHO standard using 10 different real-time quantitative CMV PCR assays run by eight different laboratories. Test panels, including aliquots of 50 patient samples (40 positive samples and 10 negative samples) and lyophilized CMV standard, were run, with each testing center using its own quantitative calibrators, reagents, and nucleic acid extraction methods. Commutability was assessed both on a pairwise basis and over the entire group of assays, using linear regression and correspondence analyses. Commutability of the WHO material differed among the tests that were evaluated, and these differences appeared to vary depending on the method of statistical analysis used and the cohort of assays included in the analysis. Depending on the methodology used, the WHO material showed poor or absent commutability with up to 50% of assays. Determination of commutability may require a multifaceted approach; the lack of commutability seen when using the WHO standard with several of the assays here suggests that further work is needed to bring us toward true consensus. Q uantitative detection of cytomegalovirus (CMV) DNA has become a standard part of care for many groups of immunocompromised patients, but particularly for transplant recipients (1-4). A host of laboratory-developed real-time PCR methods have been described for this purpose, and more recently, FDAapproved assays have become available. The benefits of such testing to trigger preemptive or therapeutic treatments or to monitor the efficacy of such treatments and determine therapeutic endpoints are widely accepted. However, benchmark values for such interventions have yet to be established, and it is now decades after the introduction of molecular diagnostics. The reasons for this lack of consensus have become clear over a number of studies which have shown poor quantitative concordance between laboratories and between methods. Several investigators have documented discordant results for human cytomegalovirus (HCMV) testing as well as for other viral load measures that depend largely upon methods developed in the laboratory (5-7). The reasons for such variability may be numerous (8); however, intuitively, different quantitative calibrators may directly relate to different quantitative results. This has been confirmed in the literature, and the importance of developing consensus standards has been well accepted (9-11) and confirmed by past experience with other viruses.The advent of the first WHO International Standard for HCMV DNA was meant to address this need (12). This material consists of a known quantity of the CMV merl...

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Section: Discussionmentioning

confidence: 99%

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Commutability of the First World Health Organization International Standard for Human Cytomegalovirus

et al. 2015

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“…The use of common secondary standards in some cases has been shown to increase agreement among laboratories using various quantitative assays (6,14,20). However, noncommutable standards may actually decrease interlaboratory/interassay agreement (22). It is clear that in some cases, some secondary standards showed similar results across different assays, and some showed improved agreement compared with the digital results rather than with the nominal values of secondary standards.…”

Section: Tablementioning

confidence: 83%

Comparative Evaluation of Three Commercial Quantitative Cytomegalovirus Standards by Use of Digital and Real-Time PCR

Hayden

Sam

et al. 2015

J Clin Microbiol

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The recent development of the 1st WHO International Standard for human cytomegalovirus (CMV) and the introduction of commercially produced secondary standards have raised hopes of improved agreement among laboratories performing quantitative PCR for CMV. However, data to evaluate the trueness and uniformity of secondary standards and the consistency of results achieved when these materials are run on various assays are lacking. Three concentrations of each of the three commercially prepared secondary CMV standards were tested in quadruplicate by three real-time and two digital PCR methods. The mean results were compared in a pairwise fashion with nominal values provided by each manufacturer. The agreement of results among all methods for each sample and for like concentrations of each standard was also assessed. The relationship between the nominal values of standards and the measured values varied, depending upon the assay used and the manufacturer of the standards, with the degree of bias ranging from ؉0.6 to ؊1.0 log 10 IU/ml. The mean digital PCR result differed significantly among the secondary standards, as did the results of the real-time PCRs, particularly when plotted against nominal log 10 IU values. Commercially available quantitative secondary CMV standards produce variable results when tested by different real-time and digital PCR assays, with various magnitudes of bias compared to nominal values. These findings suggest that the use of such materials may not achieve the intended uniformity among laboratories measuring CMV viral load, as envisioned by adaptation of the WHO standard.R outine viral load measurements have become the standard of care for many patients, particularly those with severely compromised immune systems (1-5). However, despite their widespread clinical use, current testing strategies still have many limitations. Except for HIV and hepatitis B and C viruses, there has been little standardization of the testing process. Most methods are based on real-time PCR and have a high degree of result variability, particularly when testing among institutions is compared (6-9). The reasons for this variability are myriad. Real-time PCR is a dynamic process, with quantification based on normalization of the time to signal generation to a calibration curve that is in turn based on the use of calibration material with "known" values. Variations in any part of this complex procedure might theoretically affect result accuracy or precision. In fact, several factors have been shown to play a role (10); however, the most emphasis in the literature has been placed on the lack of universally accepted calibrators (11, 12). The lack of available international quantitative standards for many of the commonly tested viral analytes has led to the use of a wide variety of materials, intuitively reducing the agreement of results when common samples have been tested by different centers. It has been widely hoped that the development of such international reference material would help improve this situation. The...

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“…Finally, the percentages of specimens that fell within various ranges were plotted (e.g., 15% of the samples were within 0.1 log 10 and 100% of the samples were within 1.0 log 10 ), as previously described (Fig. 2C) (12). This analysis revealed that the quantitative agreement between assays was unchanged when calibrated to the WHO standard.…”

Section: Iral Load Testing For Epstein-barr Virus (Ebv) Is Importantmentioning

confidence: 99%

“…Commutability refers to the ability of a reference material to have interassay properties comparable to the properties demonstrated by authentic clinical samples (9). Critically, the use of reference materials that lack commutability may reduce quantitative agreement (10)(11)(12). We therefore evaluated the commutability of the EBV WHO standard across two common real-time PCR assays, the laboratory-developed BamHI and the commercial artus EBV QIAsymphony Rotor-Gene Q (QS-RGQ) assays.…”

Section: Iral Load Testing For Epstein-barr Virus (Ebv) Is Importantmentioning

confidence: 99%

Commutability of the Epstein-Barr Virus WHO International Standard across Two Quantitative PCR Methods

et al. 2014

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Multicenter Evaluation of a Commercial Cytomegalovirus Quantitative Standard: Effects of Commutability on Interlaboratory Concordance

Cited by 34 publications

References 14 publications

Commutability of the First World Health Organization International Standard for Human Cytomegalovirus

Commutability of the First World Health Organization International Standard for Human Cytomegalovirus

Comparative Evaluation of Three Commercial Quantitative Cytomegalovirus Standards by Use of Digital and Real-Time PCR

Commutability of the Epstein-Barr Virus WHO International Standard across Two Quantitative PCR Methods

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