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FRI0068 Diagnostic value of third generation anti-citrullinated peptides antibodies in rheumatoid artritis
  1. D. Grados1,
  2. A. Riveros1,
  3. M. Martinez-Morillo1,
  4. B. Tejera1,
  5. S. Holgado1,
  6. L. Mateo1,
  7. A. Olivé1,
  8. X. Tena1,
  9. A. Teniente-Serra2,
  10. V. García-Lόpez2,
  11. E. Ruíz2,
  12. E. Martínez-Cáceres2
  1. 1Department of Rheumatology, Hospital Universitari Germans Trias I Pujol
  2. 2Department of Immunology, Lirad-Bst, Badalona, Spain

Abstract

Background Assays that detect anti-citrullinated peptides antibodies (ACPA) are considered to be more specific than rheumatoid factor in the diagnosis of rheumatoid arthritis (RA). Several tests have been developed using different antigens: first, second and third-generation cyclic-ACPA (CCP1, CCP2, CCP3) and modified citrullinated vimentin (MCV).

Objectives To investigate anti-CCP3 in a group of patients positive citrullinated vimentin antibodies (MCVA).

Methods The retrospective study was done at the university hospital with a reference population of 800,000. Atotal of 259 patients positive for IgG MCV antibodies (by ELISA) attending the outpatient rheumatology clinic were tested for anti-CCP3 (by ELISA). From the total, 182 (70.3%) of them had a rheumatic disease: RA in 121 (66.5%) and other: elderly-onset arthritis, non-filiated arthritis, connective, vasculitis, Still’s disease, espondiloarthritis, microcrystalline arthritis, polymyalgia rheumatica and sarcoidosis, in 61 (33.5%). There are 77 (29.7%) patients with other conditions (non rheumatic disease) positive for MCVA were also tested for anti-CCP3.

Results From the 121 RA patients, 106 (87.6%) were positive for anti-CCP3. In contrast, only 15 (24.6%) of the 61 patients without RA and only 4 (5.2%) of the 77 MCVA positive patients with no rheumatic disease associated were CCP3 positive. Interestingly, within the group no RA, of the 13 patients with anti-CCP3 values >60 U/ml, 6 (46.2%) were patients with palindromic rheumatism and two of them had developed RA. Specificity of anti-CCP3 for RA as compared to other rheumatic disease was 76.7%, that raised to 86.9% when comparing RA versus to non-RA (with or without another rheumatic disease). Positive and negative predictive values of anti-CCP3 for RA were 85.5% and 88.8%, respectively whereas positive predictive values for anti-MCV was 39.1%.

Conclusions Anti-CCP3 antibodies show a higher specificity for RA when compared to MCVA with a better positive predictive values, a crucial feature for a test in use for clinical practice.

Disclosure of Interest None Declared

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