PB0828 - Evaluation of within-subject variation of VWF multimers assay

Monday, July 11, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Co-Author(s)

MP

Marika Pikta, MD

Laboratory medicine physician
Department of Laboratory Medicine, North Estonia Medical Centre, Tallinn, Estonia; Department of Health Technologies, Tallinn University of Technology, Tallinn, Estonia
Tallinn, Harjumaa, Estonia

Presenting Author(s)

Timea Szanto

consultant
Coagulation Disorders Unit, Department of Hematology, Helsinki University Hospital Comprehensive Cancer Center and University of Helsinki, Helsinki, Finland
Helsinki, Uusimaa, Finland

Co-Author(s)

VB

Valdas Banys

Laboratory medicine physician
Department of Physiology, Biochemistry, Microbiology and Laboratory Medicine, Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
Vilnius, Vilniaus Apskritis, Lithuania

Background: Von Willebrand factor (VWF) multimers (VWF:MM) play a major role in the phenotypic classification of von Willebrand disease (VWD). However, there is a high error rate, inconsistent interpretations of VWF:MM profiles and false classifications even in the experienced laboratories.

Aims: The aim of this study was to evaluate the within-subject variation of VWF:MM assay using H5VW and H11VW gels (Sebia, France).

Methods: VWF:MM were subdivided as low molecular weight multimers (LMWM), intermediate molecular weight multimers (IMWM) and high molecular weight multimers (HMWM) according the manufacturer`s recommendation.
Laboratory profiles of 24 individuals referred for bleeding disorders evaluation were analyzed. For assessment of within-subject variation, samples from non-VWD individuals (n=9), low VWF (n=1), suspected VWD type 1 (n=7), suspected VWD type 2A or 2M (n=5) and Hemophilia A carriers (n=2) were collected over time and the VWF:MM evaluation was repeated twice (n=20), three (n=3) or four times (n=1).
The assessment criterion was an identical VWF:MM interpretation of results in each case (normal pattern/ lack of IMWM and HMWM/ relative decrease of HMWM).

Results: In the group with normal VWF:MM distribution, the within-subject variations for LMWM, IMWM and HMWM were 7.3%, 7.0% and 4.3%, respectively. In the group with relative decrease of HMWM, the within-subject variations for LMWM, IMWM and HMWM were 14.5%, 17.3% and 10.6%, respectively. In all cases repeated VWF:MM testing yielded identical interpretation.

Conclusion(s): Demonstrated within-subject VWF:MM variability shows reasonable repeatability of results in both non-VWD and VWD patient samples. Consistent interpretation of different follow-up samples indicates the reliability of chosen VWF:MM assay.