title: Diagnostic utility of anti-cyclic citrullinated peptide antibodies for very early rheumatoid arthritis.
abstract: OBJECTIVE
  To compare the diagnostic utility of anti-cyclic citrullinated peptide (anti-CCP) antibodies with other serological markers including rheumatoid factor (RF), anti-agalactosyl immunoglobulin G (IgG) antibody, and matrix metalloproteinase (MMP)-3 in very early rheumatoid arthritis (RA).
  
  
  METHODS
  Serum concentrations of anti-CCP antibodies, RF, anti-agalactosyl IgG antibody, and MMP-3 were measured in 262 patients with RA ("total RA") including 55 patients with disease duration of less than 6 months who had not been treated before entry ("very early RA") and 116 patients with rheumatic diseases other than RA.
  
  
  RESULTS
  The diagnostic sensitivity of anti-CCP antibodies was 82.4% in total RA and 67.3% in very early RA and was lower than that of RF (84.0% total RA, 83.6% very early RA) and anti-agalactosyl IgG antibody (90.5%, 90.9%), whereas specificity, positive predictive value, and diagnostic accuracy were the best among markers tested both in total RA and in very early RA. The presence of either anti-CCP antibodies or RF increased the sensitivity, but any combination of serological markers was not significantly better in diagnostic accuracy than anti-CCP antibodies alone. The rates of RF-positive subjects in anti-CCP antibody-negative patients both in total RA (43.5%) and in very early RA (61.1%) were higher than those of anti-CCP antibody-positive subjects in RF-negative patients (38.1% and 22.2%, for total RA and early RA, respectively).
  
  
  CONCLUSIONS
  Measurement of anti-CCP antibodies, by itself, is useful for the diagnosis of RA; however, combined use of anti-CCP antibodies with RF may be more useful than either method alone for the diagnosis of very early RA.
authors.affiliation: Department of Rheumatology, Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, National Hospital Organization, Kanagawa, Japan.t-matsui@sagamihara-hosp.gr.jp
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Matsui
authors.forename: Kota
authors.initials: K
authors.lastname: Shimada
authors.forename: Naoko
authors.initials: N
authors.lastname: Ozawa
authors.forename: Hiromi
authors.initials: H
authors.lastname: Hayakawa
authors.forename: Futoshi
authors.initials: F
authors.lastname: Hagiwara
authors.forename: Hisanori
authors.initials: H
authors.lastname: Nakayama
authors.forename: Shoji
authors.initials: S
authors.lastname: Sugii
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ozawa
authors.forename: Shigeto
authors.initials: S
authors.lastname: Tohma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001170:Arthritis, Infectious / Q000175:diagnosis; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D042241:Early Diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis; D008297:Male; D019278:Matrix Metalloproteinase 3 / Q000097:blood*; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000097:blood*
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D010456:Peptides, Cyclic; C064155:agalactosyl IGG; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor; D019278:Matrix Metalloproteinase 3