title: Automated interpretation of ANCA patterns - a new approach in the serology of ANCA-associated vasculitis.
abstract: BACKGROUND
  Indirect immunofluorescence (IIF) employing ethanol-fixed neutrophils (ethN) is still the method of choice for assessing antineutrophil cytoplasmic antibodies (ANCA) in ANCA-associated vasculitides (AAV). However, conventional fluorescence microscopy is subjective and prone to high variability. The objective of this study was to evaluate novel pattern recognition algorithms for the standardized automated interpretation of ANCA patterns.
  
  
  METHODS
  Seventy ANCA-positive samples (20 antimyeloperoxidase ANCA, 50 antiproteinase3 ANCA) and 100 controls from healthy individuals analyzed on ethN and formalin-fixed neutrophils (formN) by IIF were used as a 'training set' for the development of pattern recognition algorithms. Sera from 342 patients ('test set') with AAV and other systemic rheumatic and infectious diseases were tested for ANCA patterns using the novel pattern recognition algorithms and conventional fluorescence microscopy.
  
  
  RESULTS
  Interpretation software employing pattern recognition algorithms was developed enabling positive/negative discrimination and classification of cytoplasmic ANCA (C-ANCA) and perinuclear ANCA (P-ANCA). Comparison of visual reading of the 'test set' samples with automated interpretation revealed Cohen's kappa (κ) values of 0.955 on ethN and 0.929 on formN for positive/negative discrimination. Analysis of the 'test set' with regard to the discrimination between C-ANCA and P-ANCA patterns showed a high agreement for ethN (κ = 0.746) and formN (κ = 0.847). There was no significant difference between visual and automated interpretation regarding positive/negative discrimination on ethN and formN, as well as ANCA pattern recognition (P > 0.05, respectively).
  
  
  CONCLUSIONS
  Pattern recognition algorithms can assist in the automated interpretation of ANCA IIF. Automated reading of ethN and formN IIF patterns demonstrated high consistency with visual ANCA assessment.
authors.forename: Ilka
authors.initials: I
authors.lastname: Knütter
authors.forename: Rico
authors.initials: R
authors.lastname: Hiemann
authors.forename: Therese
authors.initials: T
authors.lastname: Brumma
authors.forename: Thomas
authors.initials: T
authors.lastname: Büttner
authors.forename: Kai
authors.initials: K
authors.lastname: Großmann
authors.forename: Marco
authors.initials: M
authors.lastname: Cusini
authors.forename: Francesca
authors.initials: F
authors.lastname: Pregnolato
authors.forename: Maria Orietta
authors.initials: MO
authors.lastname: Borghi
authors.forename: Ursula
authors.initials: U
authors.lastname: Anderer
authors.forename: Karsten
authors.initials: K
authors.lastname: Conrad
authors.forename: Dirk
authors.initials: D
authors.lastname: Reinhold
authors.forename: Dirk
authors.initials: D
authors.lastname: Roggenbuck
authors.forename: Elena
authors.initials: E
authors.lastname: Csernok
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000097:blood* / Q000175:diagnosis*; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D001330:Electronic Data Processing; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods*; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D055815:Young Adult
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic