title: Antibodies against cyclic citrullinated peptide (CCP) in psoriatic patients with or without joint inflammation.
abstract: OBJECTIVE
  To compare the prevalence of anti-CCP antibodies in psoriatic patients with and without joint inflammation, patients with early RA, and controls.
  
  
  METHODS
  Anti-CCP antibodies (cut off level 5 U/ml) were measured in 160 patients with psoriatic arthritis (PsA), 146 patients with psoriasis but no arthritic disease, 101 patients with early RA, and 102 healthy controls by ELISA.
  
  
  RESULTS
  11 (7%) patients with PsA, 75 (74%) patients with early RA, 2 (2%) healthy controls (2%), and 1 (0.7%) patient with psoriasis without arthritis had anti-CCP antibodies above the cut off level. The presence of anti-CCP antibodies was not related to radiological changes and/or deformity and functional impairment in PsA. 8/11 patients with PsA and anti-CCP antibodies had a polyarthritic disease, and all fulfilled the ACR criteria for RA at 4 year follow up. Five of these 8 patients also had manifestations such as dactylitis, DIP involvement, radiological changes associated with PsA, and/or enthesitis. In multiple logistic regression analysis with polyarthritis as the dependent variable, anti-CCP antibodies and rheumatoid factor significantly distinguished RA from PsA.
  
  
  CONCLUSIONS
  Anti-CCP antibodies were more prevalent in patients with PsA than in patients with psoriasis without arthritis, but less prevalent than in patients with early RA. Patients with PsA positive for anti-CCP antibodies more often had polyarthritic disease, but the presence of anti-CCP antibodies did not relate to radiological changes and/or deformity and functional impairment.
authors.affiliation: Department of Rheumatology, University Hospital, SE-901 85 Umea, Sweden. gerdmarie.alenius@vll.se
authors.forename: G M
authors.initials: GM
authors.lastname: Alenius
authors.forename: E
authors.initials: E
authors.lastname: Berglin
authors.forename: S
authors.initials: S
authors.lastname: Rantapää Dahlqvist
mesh_terms: D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D011565:Psoriasis / Q000276:immunology; D011859:Radiography
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide