title: Evaluation of commercial von Willebrand factor collagen binding assays to assist the discrimination of types 1 and 2 von Willebrand disease.
abstract: This study reports on the evaluation of seven commercial von Willebrand factor (VWF) collagen binding (VWF:CB) assays to potentially assist the discrimination of types 1 and 2 von Willebrand disease (VWD). Samples from 25 patients with type 1 VWD, of varying severity, were co-tested with 16 samples from patients with types 2A or 2B VWD, plus various control samples, using each commercial VWF:CB assay assessed against our standard (reference) in-house VWF:CB assay, as well as our in-house VWF antigen (VWF:Ag) and ristocetin cofactor (VWF:RCo) assays. Commercial VWF:CB assays varied in their ability to discriminate types 1 and 2A/2B VWD. The optimal VWF:CB/VWF:Ag ratio at which optimal discrimination occurred also differed between assays, with some improvements observed with some (but not all) assays following a harmonisation process that aimed to correct for different calibrator effects. Assay variability also compromised assay utility in some test occasions. Future standardisation and improvements in some commercial VWF:CB assays are needed before the VWF:CB assay can be more fully and globally utilised for discrimination of VWD types in diagnostic laboratories.
authors.affiliation: Department of Haematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, New South Wales, Australia. emmanuel.favaloro@swahs.health.nsw.gov.au
authors.forename: Emmanuel J
authors.initials: EJ
authors.lastname: Favaloro
mesh_terms: D003094:Collagen / Q000378:metabolism*; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D006801:Humans; D011237:Predictive Value of Tests; D011485:Protein Binding; D011933:Reagent Kits, Diagnostic / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D056725:von Willebrand Disease, Type 1 / Q000097:blood / Q000175:diagnosis*; D056728:von Willebrand Disease, Type 2 / Q000097:blood / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D011933:Reagent Kits, Diagnostic; D014841:von Willebrand Factor; D003094:Collagen