title: Validation of a rapid test (VWF-LIA) for the quantitative determination of von Willebrand factor antigen in type 1 von Willebrand disease diagnosis within the European multicenter study MCMDM-1VWD.
abstract: BACKGROUND
  Accurate measurement of von Willebrand factor (VWF) is a critical requirement for the diagnosis of von Willebrand disease (VWD).
  
  
  OBJECTIVE
  To evaluate the diagnostic efficiency of a rapid quantitative test for the measurement of VWF antigen (VWF:Ag) in type 1 VWD.
  
  
  METHODS
  VWF:Ag was measured with an ELISA in a robotic instrument, as a reference method, and with a fully automated latex-immunoassay (LIA) on an ACL 9000 analyser in 1,716 subjects enrolled within the Molecular and Clinical Markers for Diagnosis and Management of Type 1 von Willebrand Disease (MCMDM-1VWD) Study. Among these subjects, 1,049 were healthy controls, 281 healthy family members and 386 affected members from 127 European families with type 1 VWD.
  
  
  RESULTS
  The assay linearity range was 10-125 IU/dL for LIA (R2=0.99) and 5-133 IU/dL for ELISA (R2=0.99). The inter-assay CV for low VWF levels (approximately 30 IU/dL) was 2% for the LIA test and 8.7 % for ELISA. The sensitivity for detection of type 1 VWD affected members was 86% and the specificity 91% for LIA, 87% and 90% for ELISA. A receiver-operator (ROC) analysis disclosed only a marginal difference between the two tests, LIA having a slightly greater area under the curve (0.94 vs. 0.93, p=0.03).
  
  
  CONCLUSIONS
  VWF:Ag LIA compared well to standard ELISA in this large population of patients and controls, showing better CV. However the lower detection limit for the VWF:Ag LIA compared to the VWF:Ag ELISA means that the LIA assay is less good at discriminating between type 3 VWD and moderate type 1 VWD.
authors.affiliation: Department of Hematology, San Bortolo Hospital, Vicenza, Italy. castaman@hemato.ven.it
authors.forename: G
authors.initials: G
authors.lastname: Castaman
authors.forename: A
authors.initials: A
authors.lastname: Tosetto
authors.forename: A
authors.initials: A
authors.lastname: Cappelletti
authors.forename: A
authors.initials: A
authors.lastname: Goodeve
authors.forename: A B
authors.initials: AB
authors.lastname: Federici
authors.forename: J
authors.initials: J
authors.lastname: Batlle
authors.forename: D
authors.initials: D
authors.lastname: Meyer
authors.forename: J
authors.initials: J
authors.lastname: Goudemand
authors.forename: J C J
authors.initials: JC
authors.lastname: Eikenboom
authors.forename: R
authors.initials: R
authors.lastname: Schneppenheim
authors.forename: U
authors.initials: U
authors.lastname: Budde
authors.forename: J
authors.initials: J
authors.lastname: Ingerslev
authors.forename: S
authors.initials: S
authors.lastname: Lethagen
authors.forename: F
authors.initials: F
authors.lastname: Hill
authors.forename: I R
authors.initials: IR
authors.lastname: Peake
authors.forename: F
authors.initials: F
authors.lastname: Rodeghiero
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057205:Automation, Laboratory; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D005060:Europe; D006801:Humans; D007841:Latex Fixation Tests / Q000592:standards; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D012372:ROC Curve; D012015:Reference Standards; D015203:Reproducibility of Results; D012371:Robotics; D012680:Sensitivity and Specificity; D055815:Young Adult; D056725:von Willebrand Disease, Type 1 / Q000097:blood / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000032:analysis*
chemical_list: D015415:Biomarkers; D014841:von Willebrand Factor