title: Clinical and serological analysis of patients with positive anticyclic citrullinated Peptide antibodies referred through a Rheumatology Central Triage System.
abstract: OBJECTIVE
  Anticitrullinated protein antibodies (ACPA) are a highly specific and sensitive biomarker for the diagnosis of rheumatoid arthritis (RA). Some patients who were found to have a positive ACPA test were referred to our Rheumatology Central Triage (CT; Calgary, Alberta, Canada) for assessment by a rheumatologist. The objectives of our study were to determine the clinical accuracy of ACPA in establishing a diagnosis of RA in a real-time clinical setting.
  
  
  METHODS
  Cases that met 3 criteria were included in the study: (1) referred to the CT over 3 calendar years (n = 20,389), (2) reason for referral was a positive ACPA test (n = 568), and (3) evaluated by a certified rheumatologist (n = 314). An administrative serological database was used to retrieve specific ACPA results.
  
  
  RESULTS
  Of patients referred through our CT for evaluation of a positive ACPA test, 57.6% received a diagnosis of RA; the remainder had a variety of other diagnoses, some of which might be considered early RA (9%). The predictive values of ACPA for the diagnosis of RA were increased when rheumatoid factor (RF) results were included in the analysis. When definite and possible RA were combined and the prevalence of moderate/high ACPA was compared to all other individuals, the positive and negative predictive values for moderate/high ACPA for RA were 74.3% and 68.4%, respectively.
  
  
  CONCLUSIONS
  About 58% of patients with a positive ACPA referred through a triage system for a rheumatologist opinion received a diagnosis of RA at their first visit. RF provides additional useful information to guide the diagnosis and urgency of referral.
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Liam
authors: L
authors: Martin
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Whitney A
authors: WA
authors: Steber
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Terri L
authors: TL
authors: Lupton
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Michael
authors: M
authors: Mahler
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Christie M
authors: CM
authors: Fitch
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Jacob D
authors: JD
authors: McMillan
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc.
authors: Danielle R
authors: DR
authors: Schmidt
authors: From the Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada; and Inova Diagnostics Inc., San Diego, California, USA.L. Martin, MB, MRCPI, FRCPC, Professor of Medicine; W.A. Steber, BPE, BSc, Clinical Research Manager; T.L. Lupton, RN, Clinical Coordinator; C.M. Fitch, RN; J.D. McMillan, Research Assistant; D.R. Schmidt, Research Assistant; M.J. Fritzler, PhD, MD, FRCPC, Professor of Medicine, Faculty of Medicine, University of Calgary; M. Mahler, PhD, Vice-President, Research and Development, Inova Diagnostics Inc. fritzler@ucalgary.ca.
authors: Marvin J
authors: MJ
authors: Fritzler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000097:blood; D012219:Rheumatology; D014218:Triage; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor
keywords: ANTICYCLIC CITRULLINATED PEPTIDE ANTIBODIES; AUTOANTIBODIES; HEALTHCARE RESOURCES; REFERRAL AND CONSULTATION; RHEUMATOID ARTHRITIS; TRIAGE SYSTEM