Conversion, correction, and international scale standardization: Results from a multicenter external quality assessment study for BCR-ABL1 testing

Michael Griffiths, Simon J. Patton, Alberto Grossi, Jordan Clark, Maria Fe Paz, Emmanuel Labourier, Susanna Akiki, Rosa Ayala, Eva Barragan, Daniela Basso, Nathalie Beaufils, Dominique Bories, Jean Michel Cayuela, Marc Füllgrabe, Jean Gabert, Aytug Kizilors, Nicholas Lea, Luis Lombardia, Carole Maute, Sarah L. McCarronGuillermina Nickless, Elisa Piva, Christiane Pott, Cristina Rabascio, Daniel Rueda, Christoph Schmitt, Oliver Wachter, Lurdes Zamora

Research output: Contribution to journalArticlepeer-review


Context.-Monitoring BCR-ABL1 expression levels relative to clinically validated response criteria on the International Scale (IS) is vital in the optimal management of patients with chronic myeloid leukemia, yet significant variability remains across laboratories worldwide. Objective.-To assess method performance, interlaboratory precision, and different IS standardization modalities in representative laboratories performing routine BCRABL1 testing. Design.-Fifteen blinded test specimens with 5-level nominal BCR-ABL1 to ABL1 IS percentage ratios ranging from 5% to 0.0005% and 4-level secondary IS reference panels, the ARQ IS Calibrator Panels, were tested by relative quantitative polymerase chain reaction in 15 laboratories in 5 countries. Both raw and IS percentage ratios calculated by using local conversion factors (CFs) or analytic correction parameters (CPs) were collected and analyzed. Results.-A total of 670 valid positive results were generated. BCR-ABL1 detection was associated with variable ABL1 quality metric passing rates (P <.001) and reached at least 0.01% in 13 laboratories. Intralaboratory precision was within 2.5-fold for all sample levels combined with a relative mean difference greater than 5-fold across laboratories. International Scale accuracy was increased by using both the CF and CP standardization methods. Classification agreement for major molecular response status was 90% after CF conversion and 93% after CP correction, with precision improved by 3-fold for the CP method. Conclusions.-Despite preanalytic and analytic differences between laboratories, conversion and correction are effective IS standardization methods. Validated secondary reference materials can facilitate global diffusion of the IS without the need to perform sample exchange and improve the accuracy and precision of BCR-ABL1 quantitative measurements, including at low levels of residual disease.

Original languageEnglish
Pages (from-to)522-529
Number of pages8
JournalArchives of Pathology and Laboratory Medicine
Issue number4
Publication statusPublished - Apr 1 2015

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Medical Laboratory Technology
  • Medicine(all)


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