Abstract Number: PB1528
Meeting: ISTH 2020 Congress
Theme: Platelet Disorders and von Willebrand Disease » von Willebrand Factor Biology
Background: VWF is composed of multimers and the high-molecular-weight multimers (HMWM) carry the most important hemostastic effect. Patients with myeloproliferative neoplasms (MPN) and high platelet count (> 1500 G/l) are at risk of bleeding because of a decrease in HMWM, i.e. acquired von Willebrand disease. This is suspected when VWF ristocetin cofactor activity (VWF:RCo) is decreased. For functional assessment of VWF, aggregometry (RCo(Agg)) is considered to be the gold standard. However, this assay suffers from poor reproducibility and sensitivity at low levels of VWF and is labour intensive. Various assays for RCO have been developed in recent years.
Aims: To compare the performance of HemosIL RCo, Werfen® versus aggregometry in patients with thrombocytosis (platelets > 450G/L) in the context of MPN (T-MPN) and in patients with secondary thrombocytosis (ST).
Methods: Samples from 36 patients with MPN and 18 patients with ST were evaluated with RCo(Agg) and RCo(IL) assays. VWF antigen level (VWF:Ag), distribution of VWF multimers by electrophoresis and VWF binding capacity to collagen (CB) were also analysed for each patient.
Results: In T-MPN and ST patients, there was a significant difference between the two techniques for RCo and RCo/Ag ratio (p < 0.0001 and p < 0.0001). A majority of T-MPN patients (22/36) had RCo/Ag ratio ≤ 0.6 with HemosIL assay but not with aggregometry. In ST patients, only 6/18 patients had discordant results. Among T-MPN patients with discordant results, 5 had actually a decrease in HMWM and/or CB ≤ 0.6 versus none among the 6 ST patients with discordant results. There was a correlation between RCo(IL)/Ag ratio and platelet count in T-MPN patients but not in ST patients.
Conclusions: HemosIL RCo reagent seems to be more sensitive than aggregometry to detect a change in the profile of HMWM in T-MPN patients
To cite this abstract in AMA style:
Laporte P, Tuffigo M, Ryman A, Mansier O, Fiore M, James C. Comparison of an Automated von Willebrand Factor Activity Assay by HemosIL Werfen® with Ristocetin Cofactor Assay by Aggregometry in Thrombocytic Patients with Myeloproliferative Neoplasms or Secondary Thrombocytosis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/comparison-of-an-automated-von-willebrand-factor-activity-assay-by-hemosil-werfen-with-ristocetin-cofactor-assay-by-aggregometry-in-thrombocytic-patients-with-myeloproliferative-neoplasms-or-sec/. Accessed January 21, 2022.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/comparison-of-an-automated-von-willebrand-factor-activity-assay-by-hemosil-werfen-with-ristocetin-cofactor-assay-by-aggregometry-in-thrombocytic-patients-with-myeloproliferative-neoplasms-or-sec/