title: Is Anti Cyclic citrullinated peptide a useful laboratory test for the diagnosis of rheumatoid arthritis?
abstract: OBJECTIVE
  To evaluate Anti Cyclic citrullinated peptide (anti-CCP) and Rheumatoid Factor (RF) sensitivity and specificity in patients with Rheumatoid Arthritis (RA).
  
  
  METHODS
  Anti-CCP and RAtest for the assessment of RF have been tried out in 35 patients with RA and in a group of 42 patients whose hands were affected by arthralgic/arthritis-like symptoms.
  
  
  RESULTS
  Sensitivity of anti-CCP was 71,4% with 95,2% of specificity. RAtest sensitivity was 91,4% with specificity of 31%. Anti-CCP and RAtest both positive showed an overall 71.4% sensitivity and 95.2% specificity; sensitivity was 91.4% and specificity was 31.0%, if at least RAtest or anti-CCP resulted positive, The positive predictive value of the two test performed together was 97.0%, higher than that of anti-CCP (71.4%) and RAtest (88.5%9) alone. The negative predictive value of the two test performed together was 30.9% similar to that of the RAtest performed alone (30.9%). All patients affected by HCV related chronic liver disease were negative for anti-CCP test; 12/14 of them had RAtest positive.
  
  
  CONCLUSIONS
  Anti-CCP antibody has a diagnostic specificity higher than RF. Anti-CCP and RA tests together prove to have the some specificity as anti-CCP alone and a lower sensitivity. Sensitivity is better when at least either RAtest or anti-CCP results positive. The best positive predictive value is obtained performing both anti-CCP and RAtest. Anti-CCP is a useful laboratory marker to confirm the diagnosis of rheumatoid arthritis; it seems to be very important to differentiate patients with RA from those with HCV related arthritis.
authors.affiliation: Rheumatology Unit, Ospedale per gli Infermi di Faenza, Italia.
authors.forename: F
authors.initials: F
authors.lastname: Girelli
authors.forename: F G
authors.initials: FG
authors.lastname: Foschi
authors.forename: E
authors.initials: E
authors.lastname: Bedeschi
authors.forename: V
authors.initials: V
authors.lastname: Calderoni
authors.forename: G F
authors.initials: GF
authors.lastname: Stefanini
authors.forename: M G
authors.initials: MG
authors.lastname: Martinelli
mesh_terms: D000328:Adult; D000368:Aged; D000918:Antibody Specificity; D018771:Arthralgia / Q000209:etiology; D016918:Arthritis, Reactive / Q000175:diagnosis; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001324:Autoantigens / Q000737:chemistry / Q000276:immunology; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D003937:Diagnosis, Differential; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005260:Female; D000091344:Filaggrin Proteins; D006225:Hand; D019694:Hepatitis B, Chronic / Q000150:complications / Q000276:immunology; D019698:Hepatitis C, Chronic / Q000150:complications / Q000276:immunology; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000737:chemistry / Q000276:immunology*; D011237:Predictive Value of Tests; D011499:Protein Processing, Post-Translational; D012217:Rheumatoid Factor / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor