Verification of a semi-automated Von Willebrand factor multimer assay and its clinical utility in hiv seropositive patients

Abstract

Introduction: Accurate diagnosis and subtyping of Von Willebrand disease (VWD) is critical to informing appropriate therapy and relies on several laboratory assays, including von Willebrand factor (VWF) multimer analysis. Traditional electrophoresis methods are labour-intensive, poorly standardized, and time-consuming. A newly-introduced commercial assay, the Hydragel 5 VWF multimers kit®(Sebia, Lisses, France), aims to overcome these challenges by improving standardisation and result turnaround time. This study verified the laboratory performance of this kit. Methods: Twenty-five normal samples; fifteen abnormal samples from a specialist VWD management center; and nine external quality assurance (EQA) samples were analysed with the Hydragel 5 VWF multimers kit®. The agreement of results with the conventional in-house reference method (accuracy), inter-and intra-gel variability (reproducibility), and the limitof detection were assessed. Results: Qualitatively, there was complete concordance of the results on the Hydragel 5 VWF multimers kit® with those of manual electrophoresis on both normal and abnormal samples. On all EQA surveys the multimer results obtained with the Hydragel 5 VWF multimers kit® agreed with EQA designated results. In addition, using densitometric scanning quantitative data were produced for each sample tested. Using this data, the intra-and inter-run reproducibility were demonstrated to be acceptable. The VWF antigen concentration at which multimers were still detectable was established to be between 5% and 10%. Conclusion: The Hydragel 5 VWF multimers kit®, producing both qualitative and quantitative data, is an easy-to-use, standardised assay with acceptable analytical performance which can assist in accurate subtyping of patients with VWD.