Abstract Number: VPB0843
Meeting: ISTH 2022 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » VWF and von Willebrand Factor Disorders - Clinical Conditions
Background: Essential thrombocythemia (ET) is complicated with both thrombosis and hemorrhage. Hemorrhage often occurs ET patients with platelet count more than 100 e3/cmm, and one of the causes of hemorrhage in ET patients is thought to be acquired von Willebrand syndrome (AVWS). AVWS is characterized by abnormally von Willebrand factor ristocetin cofactor activity (VWF:Rco), and decreased VWF:Rco/VWF antigen (VWF:Ag) ratio less than 0.6.
Aims: To investigate the factors associated with decreased VWF:Rco/VWF:Ag less than 0.6 in newly diagnosed ET patients.
Methods: Records of patients who were newly diagnosed with ET according to the 2016 World Health Organization criteria between August 2018 and August 2021 at Tokai University Hachioji Hospital were reviewed. Data extracted included patients characteristics, laboratory data (e.g. complete blood cell counts, VWF:Ag, VWF:Rco, allele burden of JAL2V617F), history of thrombosis or hemorrhage, and use of antiplatelet drug at diagnosis. Retrospective analysis was performed to examine factors which effect on the VWF:Rco/VWF:Ag ratio. The ethics committee of the institutional review board approved the study.
Results: 32 patients were newly diagnosed with ET during study period. 10 of them were with VWF:Rco/VWF:Ag less than 0.6, and 22 of them were with VWF:Rco/VWF:Ag 0.6 or higher . Platelet levels of patients with VWF:Rco/VWF:Ag less than 0.6 was significantly higher than those of patients with VWF:Rco/VWF:Ag 0.6 or higher (1075+/-231 e3/cmm vs 764+/-187 e3/cmm, p=0.03). Other factors (e.g. underlying diseases, white blood cell count, hematocrit, allele burden of JAL2V617F, use of antiplatelet drug at diagnosis were not different between two groups of patients (table). The ratio of patients with VWF:Rco/VWF:Ag less than 0.6 was significantly higher in ET patients with platelet count 100 e3/cmm or more (figure).
Conclusion(s): VWF:Rco/VWF:Ag ratios were significantly low in ET patients with higher platelet count.
Table
Patient characteristics
Figure
Relationships between platelet count and VWF:Rco/VWF:Ag
To cite this abstract in AMA style:
Yokoyama K. The ratio of von Willebrand factor activity to antigen in newly diagnosed essential thrombocythemia [abstract]. https://abstracts.isth.org/abstract/the-ratio-of-von-willebrand-factor-activity-to-antigen-in-newly-diagnosed-essential-thrombocythemia/. Accessed October 1, 2023.« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-ratio-of-von-willebrand-factor-activity-to-antigen-in-newly-diagnosed-essential-thrombocythemia/