title: Comparison of second- and third-generation anti-cyclic citrullinated peptide antibodies assays for detecting rheumatoid arthritis.
abstract: BACKGROUND
  The aims of the present study were to compare the diagnostic and clinical value of seven commercially available assays for second-generation anti-cyclic citrullinated peptide (CCP2) antibodies, anti-keratin antibodies (AKA) and rheumatoid factor (RF) determination in patients with rheumatoid arthritis (RA), and to check the potential advantages of a third-generation anti-CCP (CCP3) antibodies assay.
  
  
  METHODS
  Serum samples from 120 RA patients and from 170 controls were used to determine the sensitivity, the specificity, the positive (PPV) and negative predictive values (NPV) of CCP2 and CCP3 antibodies, AKA and RF assays. The respective performances of these tests were compared using a receiver-operating characteristics (ROC) curves methodology.
  
  
  RESULTS
  We found no significant differences in sensitivity and specificity between the tested anti-CCP assays. The CCP3 antibodies assay we evaluated was not significantly more sensitive than those of the second generation. Compared with RF technique, all anti-CCP assays showed better specificity, but lower sensitivity. In contrast, while of equivalent specificity, they proved to be more sensitive than AKA in the discrimination of RA from other rheumatic diseases.
  
  
  CONCLUSIONS
  Anti-CCP antibodies determination proved to be a powerful diagnostic tool, especially in RA patients with negative AKA or RF. The investigated CCP3 antibodies assay had no better diagnostic performances than the second-generation assays.
authors.affiliation: Laboratory of Clinical Chemistry, TSI 2, 5th floor, CHU, University of Liège, Sart-Tilman, 4000 Liège, Belgium. laurence.lutteri@chu.ulg.ac.be
authors.forename: Laurence
authors.initials: L
authors.lastname: Lutteri
authors.forename: Michel
authors.initials: M
authors.lastname: Malaise
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Chapelle
mesh_terms: D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood* / Q000276:immunology; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000276:immunology; D001681:Biological Assay / Q000379:methods*; D015415:Biomarkers / Q000097:blood; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007633:Keratins / Q000097:blood* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000097:blood* / Q000276:immunology; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000097:blood* / Q000276:immunology; D012680:Sensitivity and Specificity