A two‐centre comparative evaluation of new automated assays for von Willebrand factor ristocetin cofactor activity and antigen. (12th September 2013)

• Record Type: Journal Article
• Authors: Stufano, F.; Lawrie, A. S.; La Marca, S.; Berbenni, C.; Baronciani, L.; Peyvandi, F.
• Is Part Of: Haemophilia. Volume 20:Number 1(2014:Jan.)
• Page Start: 147
• Page End: 153
• Publication Date: 2013-09-12
• Subjects: Hemophilia -- Periodicals; 616.1572005
• DOI: 10.1111/hae.12264
• Languages: English
• ISSNs: 1351-8216

Abstract

<abstract abstract-type="main" id="hae12264-abs-0001"> <title>Summary</title> <p>von Willebrand disease (VWD) is caused by a quantitative and/or qualitative deficiency of the von Willebrand factor (VWF). The laboratory diagnosis of VWD is dependent on the measurement of VWF antigen (VWF:Ag) and ristocetin cofactor activity (VWF:RCo). The aim of this study was to undertake a two‐centre evaluation of two new automated VWF:Ag and VWF:RCo assays systems from Instrumentation Laboratory (Bedford, USA). Using the two new analytical systems that operated with different detection principles: immunoturbidimetric (TOP500 analyser) and chemiluminescent (AcuStar analyser), VWF:Ag and VWF:RCo levels were determined in samples from 171 healthy normal subjects, 80 VWD patients (16 type 1, 58 type 2 and 6 type 3) and 7 acquired von Willebrand syndrome patients. With commercial lyophilized normal and pathological plasmas VWF: Ag and VWF:RCo assays performed on both analysers exhibited low levels of inter‐assay imprecision (AcuStar: CV% range 3.3–6.9; TOP500: CV% range 2.6–6.3). Samples from normal healthy subjects (range: VWF:Ag 44.6–173.9 IU dL<sup>−1</sup>; VWF:RCo 43.1–191.5 IU dL<sup>−1</sup>) and patients (range: VWF:Ag <0.3–115.1 IU dL<sup>−1</sup>; VWF:RCo <0.5–57.2 IU dL<sup>−1</sup>) showed a good correlation between the two VWF:Ag and VWF:RCo methods (<italic>r</italic><sub>s</sub> = 0.92 and 0.82 respectively), with only a few inconsistent cases among the patients' samples evaluated. The chemiluminescent assays had a lower limit of detection for both VWF:Ag and VWF:RCo compared to immunoturbidimetric tests (0.3 IU dL<sup>−1</sup> vs. 2.2 IU dL<sup>−1</sup> and 0.5 IU dL<sup>−1</sup> vs. 4.4 IU dL<sup>−1</sup> respectively). The TOP500 and AcuStar VWF:Ag and VWF:RCo assays were precise and compare well between centres, making these systems suitable for the diagnosis of VWD in non‐specialized and reference laboratories.</p> </abstract>