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    Poster Networking

    Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies

    Poster Networking Session

    PB0858 - Evaluation of automated chemiluminescent von Willebrand factor assays in the diagnosis of von Willebrand disease

    Monday, June 26, 2023
    18:30 – 19:30 ET
    Room: Exhibition
    Background: Diagnosis and classification of von Willebrand disease (VWD) requires combination of von Willebrand factor (VWF) activity assays and VWF antigen (VWF:Ag). Platelet dependent VWF activity assays include Ristocetin cofactor assay (VWF:RCo) and newer assays like VWF:Gp1R and VWF:Gp1bM. Recent guidelines suggest use of Collagen binding assay (CBA) for differentiation of type 2A vs 2M. The ACL Bioflash/AcuStar (Instrumentation Laboratories) is capable of performing VWF:Ag, VWF:Gp1bR and CBA by chemiluminescent assay (CLIA) where results are available in short turnaround time.

    Aims: To evaluate the automated chemiluminescent VWF assays in cases of VWD and low VWF levels on ACL Bioflash analyser.

    Methods: This was an observational study where cases diagnosed with type 1&2 VWD and low VWF levels (30-50 IU/dL) from April to December 2022 were included. Data was available for 28 cases, wherein VWF:Ag assay (done by in-house ELISA, latex immunoassay by HemosIL and CLIA), Platelet dependent VWF activity assay (VWF:RCo by Siemens and VWF:Gp1R by CLIA) and CBA by CLIA.

    Results: There was a total of 28 cases which included 14 cases of type 2A, 4 type 1, 1 each of type 2B and 2M and 8 cases of low VWF. In 14 cases, VWF:RCo was below limit of detection and hence differentiation of type 2 vs 1 VWD was not possible. Detectable levels of VWF:Gp1R was present in 13 of 14 cases, enabling proper classification. The mean (SD) CBA/VWF:Ag ratio in type 2A/2B was 0.29 (0.24) and in type 1/low VWF cases was 1.1 (0.17). One case of type 2M had a VWF:Gp1R/VWF:Ag ratio of 0.36 and CBA/VWF:Ag ratio of 0.97. There was good correlation between VWF:Ag by CLIA and ELISA method (r=0.96), and between VWF:RCo and VWF:Gp1bR (r=0.83).

    Conclusion(s): The addition of CLIA based VWF activity assays allowed diagnosis and sub-classification of VWD in an efficient manner with a short turnaround time.