Related Experiment Video
Updated: Mar 8, 2026
Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
Validation of automated latex von Willebrand factor activity assay in a new prospective study including
M Ettel1, M A Nardi1,2, L McVoy1
1Department of Pathology, New York University School of Medicine, New York, NY, USA.
Introduction:
Von Willebrand disease (VWD) is the most prevalent inherited bleeding disorder. Diagnosis requires measurement of VWF-platelet binding function, for which VWF ristocetin cofactor activity (VWF:RCo) is the reference method. Recently, an automated latex particle-enhanced immunoturbidimetric von Willebrand factor activity assay (VWF:Ab) has been validated showing superior characteristics. We further validate VWF:Ab in a prospective study including post-treatment patient samples.
Methods:
A total of 1151 samples were collected from patients tested for VWD, including 119 samples from patients treated with desmopressin or VWF replacement product. All samples were tested for VWF:Ab and VWF:RCo, and the methods were compared using linear regression. Imprecision, linearity and lower detection limit were determined for both assays.
Results:
VWF:Ab showed improved precision compared to VWF:RCo. Linear regression of VWF:Ab and VWF:RCo across all samples exhibited good agreement (R2 = 0.89) with statistical significance (P < 0.001) and bias of -8.7. Concordance was high in classifying samples as normal or abnormal. Analysis of treated samples showed excellent agreement (R2 = 0.91) with statistical significance (P < 0.001) and bias of -4.3.
Conclusions:
Our analysis validates the VWF:Ab assay in a prospective study of a large cohort of patient samples and extends these results to post-treatment patient samples.
