title: A commutable cytomegalovirus calibrator is required to improve the agreement of viral load values between laboratories.
abstract: BACKGROUND
  Viral load testing for cytomegalovirus (CMV) is an important diagnostic tool for the management of transplant recipients and immunocompromised individuals; however, inconsistency among laboratories in quantitative measurements of viral load limits interinstitutional comparisons. These inconsistencies stem from the lack of assays cleared by the US Food and Drug Administration, the absence of international standards, the wide variety of CMV-extraction and -detection methods, and differences in materials used for calibration. A critical component of standardization is the use of calibrators that are traceable and commutable.
  
  
  METHODS
  Bland-Altman plots and prediction ellipses were used to test the commutability of 2 CMV calibrators for 2 different quantification methods.
  
  
  RESULTS
  Tests with 2 methods showed 1 calibrator to be commutable and the other to be noncommutable. The results for the commutable calibrator were within the 95% prediction interval of the clinical samples in the Bland-Altman plot and within the 95% prediction ellipse for a simulated commutable calibrator, whereas the results for the noncommutable calibrator were not within these prediction intervals. When used to calibrate patient results, only the commutable calibrator, the OptiQuant CMV(tc) Calibration Panel, significantly improved the comparability of viral loads for the 2 different measurement methods.
  
  
  CONCLUSIONS
  This study demonstrates that an important goal in the effort to improve healthcare for patients with CMV-related disease is the establishment of traceable and commutable reference materials, including both calibrators and controls. .
authors: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA. acalien@emory.edu
authors: Angela M
authors: AM
authors: Caliendo
authors: Mona D
authors: MD
authors: Shahbazian
authors: Carl
authors: C
authors: Schaper
authors: Jessica
authors: J
authors: Ingersoll
authors: Deborah
authors: D
authors: Abdul-Ali
authors: Jerry
authors: J
authors: Boonyaratanakornkit
authors: Xiao-Li
authors: XL
authors: Pang
authors: Julie
authors: J
authors: Fox
authors: Jutta
authors: J
authors: Preiksaitis
authors: E Ralf
authors: ER
authors: Schönbrunner
mesh_terms: D002138:Calibration; D003587:Cytomegalovirus / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000097:blood* / Q000821:virology*; D004279:DNA, Viral / Q000032:analysis; D006801:Humans; D019562:Viral Load / Q000379:methods* / Q000592:standards*
chemical_list: D004279:DNA, Viral