title: Performance evaluation and multicentre study of a von Willebrand factor activity assay based on GPIb binding in the absence of ristocetin.
abstract: The functional activity of von Willebrand factor (VWF) is most frequently measured by using the ristocetin cofactor assay (VWF:RCo). However, the method's drawbacks include unsatisfactory precision, sensitivity and availability of automated system applications. We have developed an alternative assay (INNOVANCE VWF Ac) that is based on the binding of VWF to recombinant glycoprotein Ib (GPIb). Two gain-of-function mutations were introduced into a GPIb fragment, allowing an assay format without ristocetin. Fully automated assay applications are available for the BCS/BCS XP systems and the Sysmex CS-2000i, Sysmex CA-7000, Sysmex CA-1500 and Sysmex CA-560 systems.The INNOVANCE VWF Ac assay measuring range extends from 4 to 600% VWF for all systems except the Sysmex CA-560 system. Within-device precision values were found to be between 2 and 7%. The limit of detection was below 2.2% VWF. In a study on the BCS XP system, a total number of 580 sample results yielded a correlation to the VWF:RCo assay of r equal to 0.99 (slope = 0.96). Very similar results were observed when von Willebrand disease samples type 1, 2A, 2B, 2M, 2N and 3 were investigated with the new assay and the VWF:RCo assay. The excellent performance data and comparability to VWF:RCo, together with the ease of use, led us to the conclusion that the ristocetin cofactor assay can be replaced by the new GPIb-binding assay to reliably diagnosing patients with von Willebrand disease.
authors.affiliation: aSiemens Healthcare Diagnostics Products GmbH, Assay Development, Marburg bHemostaseology, Medilys Laborgesellschaft mbH, Hamburg, Germany cKantonsspital Aarau, Zentrum für Labormedizin, Aarau, Switzerland dDepartment of Paediatric Haematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany eCenter for Clinical Laboratories, The Mount Sinai Hospital and Medical School, New York, USA.
authors.forename: Juergen
authors.initials: J
authors.lastname: Patzke
authors.forename: Ulrich
authors.initials: U
authors.lastname: Budde
authors.forename: Andreas
authors.initials: A
authors.lastname: Huber
authors.forename: Adriana
authors.initials: A
authors.lastname: Méndez
authors.forename: Heidrun
authors.initials: H
authors.lastname: Muth
authors.forename: Tobias
authors.initials: T
authors.lastname: Obser
authors.forename: Ellinor
authors.initials: E
authors.lastname: Peerschke
authors.forename: Matthias
authors.initials: M
authors.lastname: Wilkens
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schneppenheim
mesh_terms: D000328:Adult; D000368:Aged; D057205:Automation, Laboratory; D001681:Biological Assay / Q000592:standards*; D005260:Female; D006801:Humans; D057230:Limit of Detection; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D009154:Mutation; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry* / Q000235:genetics; D011933:Reagent Kits, Diagnostic / Q000592:standards; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D015203:Reproducibility of Results; D012310:Ristocetin / Q000737:chemistry; D014842:von Willebrand Diseases / Q000097:blood / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000032:analysis* / Q000378:metabolism
chemical_list: D019038:Platelet Glycoprotein GPIb-IX Complex; D011933:Reagent Kits, Diagnostic; D011994:Recombinant Proteins; D014841:von Willebrand Factor; D012310:Ristocetin