{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T23:22:49Z","timestamp":1776381769056,"version":"3.51.2"},"reference-count":16,"publisher":"Georg Thieme Verlag KG","issue":"06","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Semin Thromb Hemost"],"published-print":{"date-parts":[[2022,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Von Willebrand factor (VWF) level and\/or function is altered in von Willebrand disease (VWD), the most common heritable bleeding disorder worldwide. Laboratory assessment of VWF is continually evolving. Historically, the primary method for the assessment of VWF platelet-binding activity was the ristocetin cofactor assay (VWF:RCo). Contemporary alternative measures of VWF platelet-binding activity include VWF:GPIbR (recombinant; using ristocetin), VWF:GPIbM (recombinant; gain-of-function mutant), and monoclonal antibody. Recently, the American Society of Hematology, International Society on Thrombosis and Haemostasis, National Hemophilia Foundation, and World Federation of Hemophilia collaboration issued guidelines recommending the use of newer assays of VWF platelet-binding activity (VWF: GPIbM, VWF: GPIbR) over VWF:RCo, given known limitations of the VWF:RCo assay. Despite this recommendation, the newer VWF:GPIbM and VWF:GPIbR assays are not United States Food and Drug Administration cleared, limiting their availability in the United States. We sought to assess assay utilization trends, agreement of VWF testing methods, and imprecision of VWF testing (based on assigned sample type) from the College of American Pathologists Proficiency Testing Surveys. The analysis confirms that, while VWF antigen testing has low imprecision, the various VWF activity assays have significant interassay variability, with VWF:RCo showing greater imprecision than the newer GPIb-binding assays. The overall trends in assay utilization reflect the barriers to complete compliance with modern VWD diagnostic guidelines in North America.<\/jats:p>","DOI":"10.1055\/s-0042-1749591","type":"journal-article","created":{"date-parts":[[2022,9,2]],"date-time":"2022-09-02T22:50:01Z","timestamp":1662159001000},"page":"690-699","source":"Crossref","is-referenced-by-count":11,"title":["Analysis of College of American Pathologists von Willebrand Factor Proficiency Testing Program"],"prefix":"10.1055","volume":"48","author":[{"given":"Eric","family":"Salazar","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, UT Health San Antonio, San Antonio, Texas"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thomas A.","family":"Long","sequence":"additional","affiliation":[{"name":"Department of Biostatistics, College of American Pathologists, Northfield, Illinois"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kristi Johnson","family":"Smock","sequence":"additional","affiliation":[{"name":"Department of Pathology and ARUP Laboratories, University of Utah, Salt Lake City, Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Geoffrey D.","family":"Wool","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Chicago, Chicago, Illinois"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marian","family":"Rollins-Raval","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of New Mexico, Albuquerque, New Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dong","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Neil Selwyn","family":"Harris","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Florida, Gainesville, Florida"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Clarence W.","family":"Chan","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Chicago Medical Center, Chicago, Illinois"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John D.","family":"Olson","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, UT Health San Antonio, San Antonio, Texas"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huy P.","family":"Pham","sequence":"additional","affiliation":[{"name":"Seattle Apheresis Collection Center, National Marrow Donor Program (NMDP)Seattle, Washington"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jacob","family":"Ritter","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, UT Health San Antonio, San Antonio, Texas"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Unold","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amanda Matzke","family":"VanSandt","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Oregon Health & Science University, Portland, Oregon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrew Jackson","family":"Goodwin IV","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Vermont Medical Center, Burlington, Vermont"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"194","published-online":{"date-parts":[[2022,9,2]]},"reference":[{"issue":"10","key":"ref1","doi-asserted-by":"crossref","first-page":"2103","DOI":"10.1111\/j.1538-7836.2006.02146.x","article-title":"Update on the pathophysiology and classification of von Willebrand disease: a report of the Subcommittee on von Willebrand Factor","volume":"4","author":"J E Sadler","year":"2006","journal-title":"J Thromb Haemost"},{"issue":"06","key":"ref2","doi-asserted-by":"crossref","first-page":"1103","DOI":"10.1016\/j.hoc.2021.07.005","article-title":"Acquired von Willebrand Syndrome","volume":"35","author":"A L Langer","year":"2021","journal-title":"Hematol Oncol Clin North Am"},{"issue":"02","key":"ref3","doi-asserted-by":"crossref","first-page":"454","DOI":"10.1182\/blood.V69.2.454.454","article-title":"Epidemiological investigation of the prevalence of von Willebrand's disease","volume":"69","author":"F 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