Volume 9 Supplement 2
Diagnostic value of different anti-citrullinated peptides antibodies in rheumatoid arthritis
© Ruiz-Ortiz de Arrizabaleta et al; licensee BioMed Central Ltd. 2011
Published: 23 November 2011
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).
To investigate anti-CCP3 in a group of patients positive citrullinated vimentin antibodies (MCVA).
Patients and methods
A total of 259 patients positive for IgG MCVA+ attending the outpatient rheumatology clinic of a single general hospital (HUGTiP) were tested for anti-CCP3 (by ELISA). From the total, 182 (70.3%) of them had a rheumatic disease (RD): RA in 121 (66.5%) and other RDs in 61 (33.5%). 77 (29.7%) patients with other conditions positive for MCVA were also tested for anti-CCP3.
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+ patients with no RD 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 cases of palindromic rheumatism and two of them had developed RA. Specificity of anti-CCP3 for RA as compared to other RDs was 76.7%, that raised to 86.9% when comparing RA versus to non-RA (with or without another RDs). Positive and negative predictive values (PPV, NPV) of anti-CCP3 for RA were 85.5% and 88.8%, respectively whereas PPV for anti-MCV was 39.1%.
Anti-CCP3 antibodies show a higher specificity for RA when compared to MCVA with a better PPV, a crucial feature for a test in use for clinical practice.
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.