Semin Thromb Hemost 2006; 32(5): 499-504
DOI: 10.1055/s-2006-947864
Copyright © 2006 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.

External Peer Review Quality Assurance Testing in von Willebrand Disease: The Recent Experience of the United States College of American Pathologists Proficiency Testing Program

Timothy E. Hayes1 , John T. Brandt2 , Wayne L. Chandler3 , Charles S. Eby4 , Kandice Kottke-Marchant5 , Jayashree Krishnan6 , Jerry B. Lefkowitz7 , John D. Olson8 , Chad R. Rund9 , Elizabeth M. Van Cott10 , Mark T. Cunningham11
  • 1Department of Pathology and Laboratory Medicine, Maine Medical Center, Portland, Maine
  • 2Eli Lilly Corporate Center, Indianapolis, Indiana
  • 3Department of Laboratory Medicine, University of Washington, Seattle, Washington
  • 4Department of Pathology, Washington University School of Medicine, St. Louis, Missouri
  • 5Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, Ohio
  • 6Department of Pathology, Washington Hospital Center, Washington, District of Columbia
  • 7Department of Pathology, University of Colorado Health Sciences Center, Denver, Colorado
  • 8Department of Pathology, University of Texas Health Sciences Center, San Antonio, Texas
  • 9Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
  • 10Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
  • 11Department of Pathology, University of Kansas Medical Center, Kansas City, Kansas
Further Information

Publication History

Publication Date:
24 July 2006 (online)

ABSTRACT

The U.S. College of American Pathologists (CAP) has conducted a focused study of the proficiency testing for von Willebrand disease (vWD) analysis from 2003 to 2005. This report summarizes the findings regarding the accuracy and precision of the various assays at different analyte levels, as well as the influence of the reference material used to construct the assay standard curve. The results show that testing of von Willebrand factor (vWF):antigen (vWF:Ag) and ristocetin cofactor activity (vWF:RCo) is reasonably accurate, with all-method mean values falling within 3.2 and 5.6%, respectively, of the International Society on Thrombosis and Haemostasis Secondary Coagulation Standard (lot 2) assigned values. vWF:Ag measurements are reasonably precise (all-method coefficients of variation [CVs] = 10.7 to 15.1%), even at lower levels of vWF. The highest precision was observed for immunoturbidometric assays (CVs, 6.3 to 9.7%). vWF:RCo measurements are less precise (all-method CVs, 23.3 to 30.9%). The reference materials used in the standard curves for immunoturbidometric vWF:Ag assays appear to have accurately assigned vWF values for the majority of commercial suppliers.

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Timothy HayesD.V.M. M.D. 

Department of Pathology and Laboratory Medicine, Maine Medical Center

22 Bramhall St, Portland, ME 04102

Email: hayest@mmc.org