Establishment and characterization of a new and stable collagen‐binding assay for the assessment of von W illebrand factor activity

Summary Introduction Laboratory diagnosis of von W illebrand disease ( VWD ) requires determination of both von W illebrand factor ( VWF ) protein levels and activity. Current VWF activity tests include the ristocetin cofactor assay and the collagen‐binding assay ( VWF : CB ). The goal of this investigation is to characterize a new collagen‐binding assay and to determine its effectiveness in identifying VWD . Methods Analytical studies were carried out to characterize the performance of a new VWF : CB ELISA . Additionally, samples from a normal population were tested as were well‐characterized type 1 and type 2 VWD samples. Results Repeatability and within‐laboratory precision studies resulted in coefficients of variation ( CV s) of ≤11%. A linear range of 1–354% (0.01–3.54  IU / mL ) was determined, along with a limit of detection and a lower limit of quantitation of 1.6% and 4.0% (0.016 and 0.04  IU / mL ), respectively. Samples tested from apparently healthy individuals resulted in a normal range of 54–217% (0.54–2.17  IU / mL ). Known VWD type 1 and type 2 samples were also analyzed by the ELISA , with 99% of samples having VWF : CB below the normal reference range and an estimated 96% sensitivity and 87% specificity using a VWF collagen‐binding/antigen cutoff ratio of 0.50. Conclusion This new VWF : CB ELISA provides an accurate measure of collagen‐binding activity that aids in the diagnosis and differentiation of type 1 from type 2 VWD .