title: Detection of antineutrophil cytoplasmic antibodies (ANCAs): a multicentre European Vasculitis Study Group (EUVAS) evaluation of the value of indirect immunofluorescence (IIF) versus antigen-specific immunoassays.
abstract: OBJECTIVE
  This multicentre study was performed to evaluate the diagnostic accuracy of a wide spectrum of novel technologies nowadays available for detection of myeloperoxidase (MPO) and proteinase 3 (PR3)-antineutrophil cytoplasmic antibodies (ANCAs).
  
  
  METHODS
  Sera (obtained at the time of diagnosis) from 251 patients with ANCA-associated vasculitis (AAV), including granulomatosis with polyangiitis and microscopic polyangiitis, and from 924 disease controls were tested for the presence of cytoplasmic pattern/perinuclear pattern and atypical ANCA (A-ANCA) by indirect immunofluorescence (IIF) (at two sites) and for the presence of PR3-ANCA and MPO-ANCA by eight different immunoassays.
  
  
  RESULTS
  The area under the curve (AUC) of the receiver operating characteristic curve to discriminate AAV from controls was 0.923 (95% CI 0.902 to 0.944) and 0.843 (95% CI 0.814 to 0.871) for the two IIF methods. For the antigen-specific immunoassays, the AUC varied between 0.936 (95% CI 0.912 to 0.960) and 0.959 (95% CI 0.941 to 0.976), except for one immunoassay for which the AUC was 0.919 (95% CI 0.892 to 0.945).
  
  
  CONCLUSIONS
  Our comparison of various ANCA detection methods showed (i) large variability between the two IIF methods tested and (ii) a high diagnostic performance of PR3-ANCA and MPO-ANCA by immunoassay to discriminate AAV from disease controls. Consequently, dual IIF/antigen-specific immunoassay testing of each sample is not necessary for maximal diagnostic accuracy. These results indicate that the current international consensus on ANCA testing for AAV needs revision.
authors.affiliation: Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Damoiseaux
authors.affiliation: Department of Rheumatology and Immunology, Klinikum Bad Bramstedt, Bad Bramstedt, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Csernok
authors.affiliation: Department of Autoimmune Serology, Statens Seruminstitute, Copenhagen, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Rasmussen
authors.affiliation: Rheumazentrum Schleswig-Holstein Mitte, Neumünster, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Moosig
authors.affiliation: Department of Internal Medicine, Section Nephrology and Immunology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: van Paassen
authors.affiliation: Department of Rheumatology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Baslund
authors.affiliation: Clinical Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium.|Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Vermeersch
authors.affiliation: Clinical Department of General Internal Medicine, Research Department of Microbiology and Immunology, Laboratory of Clinical Infectious and Inflammatory Disorders, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Blockmans
authors.affiliation: Maastricht University, Maastricht, The Netherlands.
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Cohen Tervaert
authors.affiliation: Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium.|Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
mesh_terms: D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000097:blood* / Q000175:diagnosis*; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D019540:Area Under Curve; D016022:Case-Control Studies; D019084:Fluorescent Antibody Technique, Indirect; D007118:Immunoassay / Q000379:methods; D053146:Myeloblastin / Q000276:immunology*; D009195:Peroxidase / Q000276:immunology*; D012372:ROC Curve
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D009195:Peroxidase; D053146:Myeloblastin
keywords: Autoantibodies; Autoimmune Diseases; Systemic vasculitis