title: What is the significance in routine care of c-ANCA/PR3-ANCA in the absence of systemic vasculitis? A case series.
abstract: OBJECTIVE
  ANCA has come to play an important role in diagnosing vasculitis. In selected populations c-ANCA/PR3-ANCA has a high specificity and sensitivity for vasculitis. In clinical practice, how individuals with c-ANCA/PR3-ANCA but without sufficient evidence of systemic vasculitis should be managed is unclear. We therefore retrospectively assessed the disease panorama and outcome in a consecutive series of individuals with c-ANCA/PR3-ANCA, and studied in detail those individuals who turned out not to fulfil criteria for vasculitic disease.
  
  
  METHODS
  The study population consisted of 74 consecutive patients who all had a positive test for C-ANCA and PR3-ANCA between 1992 and 2002 at the Immunology laboratory at Uppsala University Hospital, Sweden. The patients' medical files were reviewed and their diagnosis re-evaluated through June 2006.
  
  
  RESULTS
  18 of the 74 ANCA-positive individuals did not present clinical evidence supportive of, or insufficient to support, a diagnosis of systemic vasculitis, but presented a range of other diseases. During a mean follow-up of 6.8 years, none of these 18 patients developed vasculitis.
  
  
  CONCLUSIONS
  Individuals with a positive c-ANCA and PR3-ANCA but no vasculitis at the time of testing run an unknown but likely small risk of later developing vasculitis. In this group, a positive ANCA may represent background noise (borderline titres) or be a marker of inflammatory activity rather than of vasculitic disease (high titres).
authors.affiliation: Department of Rheumatology, Uppsala University Hospital, Uppsala, Sweden. ann.kataja.knight@akademiska.se
authors.forename: A
authors.initials: A
authors.lastname: Knight
authors.forename: A
authors.initials: A
authors.lastname: Ekbom
authors.forename: L
authors.initials: L
authors.lastname: Brandt
authors.forename: J
authors.initials: J
authors.lastname: Askling
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000032:analysis* / Q000276:immunology; D018450:Disease Progression; D005189:False Positive Reactions; D005260:Female; D014890:Granulomatosis with Polyangiitis / Q000175:diagnosis*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D053146:Myeloblastin / Q000276:immunology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014657:Vasculitis / Q000175:diagnosis / Q000188:drug therapy; D055815:Young Adult
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D053146:Myeloblastin