title: Performance of two strategies for urgent ANCA and anti-GBM analysis in vasculitis.
abstract: BACKGROUND
  In anti-neutrophil cytoplasmic antibodies (ANCA) associated small vessel vasculitis (AAV), rapid testing for ANCA and anti-glomerular basement membrane (GBM) antibodies may be beneficial for therapeutic purpose.
  
  
  OBJECTIVE
  We analysed the diagnostic performance of two rapid ANCA and anti-GBM test methods in 260 patients with suspected AAV.
  
  
  METHODS
  Between January 2004 and November 2010, we analysed 260 samples by qualitative Dotblot (Biomedical Diagnostics); retrospective analysis followed with directly coated highly sensitive automated Phadia ELiA and ELiA anti-GBM. Results were related to the final clinical diagnosis and compared with routine capture ELISA.
  
  
  RESULTS
  Seventy-four patients had a final diagnosis of AAV (n=62) or anti-GBM disease (n=12). Both Dotblot and ELiA detected all 12 cases of anti-GBM disease; 2 false positive results were found. Dotblot detected ANCA in 56 of 62 AAV patients (sensitivity 90%, NPV 97%), and showed 5 false positives (specificity 97%, PPV 90%). The Phadia ELiA anti-PR3(s) or anti-MPO(s) was positive in 57 of 62 AAV patients (sensitivity 92%, NPV 97%), and had 5 false positives (specificity 97%, PPV 88%). Routine capture ELISA was equally accurate (sensitivity 94%, specificity 97%, PPV 88%, NPV 98%).
  
  
  CONCLUSIONS
  The Dotblot and Phadia ELiA on anti-GBM, anti-PR3(s) and anti-MPO(s) performed excellently; results were almost identical to routine ELISA. When suspicion of AAV or anti-GBM disease is high and diagnosis is urgently needed, both tests are very powerful for rapid serological diagnosis. Further studies have to confirm the test performances in samples routinely presented for ANCA testing and in follow-up of positive patients.
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Groningen, The Netherlands. Electronic address: a.a.e.joode@umcg.nl.
authors.forename: Anoek A E
authors.initials: AA
authors.lastname: de Joode
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, The Netherlands.
authors.forename: Caroline
authors.initials: C
authors.lastname: Roozendaal
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, The Netherlands.
authors.forename: Marcel J
authors.initials: MJ
authors.lastname: van der Leij
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, The Netherlands.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Bungener
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Groningen, The Netherlands.
authors.forename: Jan Stephan F
authors.initials: JS
authors.lastname: Sanders
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Groningen, The Netherlands.
authors.forename: Coen A
authors.initials: CA
authors.lastname: Stegeman
mesh_terms: D000328:Adult; D000368:Aged; D019867:Anti-Glomerular Basement Membrane Disease / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D015331:Cohort Studies; D042241:Early Diagnosis; D061345:Early Medical Intervention; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D001323:Autoantibodies; D007166:Immunosuppressive Agents; C051951:antiglomerular basement membrane antibody
keywords: Dotblot; ELISA; ELiA; Indirect immunofluorescence; Serology; Systemic vasculitis