title: Easy and accurate diagnosis of rheumatoid arthritis using anti-cyclic citrullinated peptide 2 antibody, swollen joint count, and C-reactive protein/rheumatoid factor.
abstract: OBJECTIVE
  To determine an easy-to-use diagnostic criterion for early rheumatoid arthritis (RA) that may be useful for general physicians, using anti-cyclic citrullinated peptide (CCP) antibody.
  
  
  METHODS
  We prospectively studied 435 patients who first visited the hospital with arthritic symptoms within 24 months, including 264 visitors within 6 months. The diagnosis was made on their first visit by examination and laboratory tests including anti-CCP antibodies, rheumatoid factor (RF) and C-reactive protein (CRP), and radiograph.
  
  
  RESULTS
  The diagnostic specificity and positive predictive value (PPV) of anti-CCP2 assay were 94.9% and 87.8%, respectively, and those of anti-CCP2 plus RF were 96.9% and 90.9% for the patients who first visited having morning stiffness, arthralgia, and/or joint swelling within 3 months from onset (n = 165). For the patients who first visited later, but within 24 months from onset (n = 260), the diagnostic specificity and PPV were extremely high, 98.7% and 95.5%, when anti-CCP2 assay was coevaluated with RF, CRP, and more than 3 swollen joints. Respective combinations of anti-CCP2 assay plus either 2 of 3 measures were also highly specific.
  
  
  CONCLUSIONS
  A diagnostic criterion including anti-CCP2 assay in combination with RF, CRP, and/or swollen joints is less sensitive but highly specific, and accurately predicts future development of RA among those with arthritic symptoms who first consulted doctors within 2 years after onset. It should be highly useful for the general physician without special techniques or devices.
authors.affiliation: Department of Rheumatology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamane
authors.forename: Akira
authors.initials: A
authors.lastname: Hashiramoto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Ken
authors.initials: K
authors.lastname: Tsumiyama
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Miura
authors.forename: Kazuko
authors.initials: K
authors.lastname: Shiozawa
authors.forename: Kazuo
authors.initials: K
authors.lastname: Chihara
authors.forename: Shunichi
authors.initials: S
authors.lastname: Shiozawa
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007596:Joints / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012217:Rheumatoid Factor / Q000097:blood*; D012720:Severity of Illness Index
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D002097:C-Reactive Protein; D012217:Rheumatoid Factor