Published in:
01-01-2008 | Original Article
A comparison of the frequency of antibodies to cyclic citrullinated peptides using a third generation anti-CCP assay (CCP3) in systemic sclerosis, primary biliary cirrhosis and rheumatoid arthritis
Authors:
Mittermayer Santiago, Murray Baron, Kiyomitsu Miyachi, Marvin J. Fritzler, M. Abu-Hakima, S. Leclercq, M. Bell, M. Hudson, J-P. Mathieu, S. Taillefer, N. Jones, P. Docherty, M. Khraishi, J. Markland, J. Pope, D. Robinson, D. Smith, E. Sutton
Published in:
Clinical Rheumatology
|
Issue 1/2008
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Abstract
The objective was to investigate the frequency of anti-cyclic citrullinated peptides (CCP) antibodies in systemic sclerosis (SSc) and primary biliary cirrhosis (PBC), utilizing a new “third generation” anti-CCP ELISA (anti-CCP3) kit and a conventional anti-CCP2 assay. Patients with PBC, SSc, RA, and normal controls were included in the study. Serum samples were screened for autoantibodies by indirect immunofluorescence (IIF), antibodies to CCP by a second- and third-generation ELISA, antibodies to “scleroderma” antigens (CENP B, Scl-70, PM/Scl and fibrillarin—Scl-34) by a line immunoassay (LIA), and IgM RF by ELISA. The frequency of anti-CCP2 antibodies in SSc and PBC samples was 14.8% (11/74) and 6.2% (5/80), respectively, and the frequency of anti-CCP3 antibodies in SSc was 13.5% (10/74) and in PBC was 3.7% (3/80). By comparison, in the RA group the frequency of anti-CCP3 and anti-CCP2 antibodies was 79.1% (38/48) and 77% (37/48), respectively. Anti-CCP3 ELISA had a sensitivity, specificity, and positive and negative likelihood ratios (LR) of 79% (95% confidence interval [CI] = 64–89%), 93% (95% CI = 88–96%), 11.8 (95% CI = 6.8–20.3), and 0.22 (95% CI = 0.12–0.38), respectively. By comparison, the anti-CCP2 assay had a sensitivity, specificity, and positive and negative LRs of 77% (95% CI = 62–87), 90% (95% CI = 85–94), 8.3 (95% CI = 5.2–13.2), and 0.25 (95% CI = 0.15–0.42), respectively. In patients with SSc, there was an association of anti-CCP2 antibodies with the presence of arthritis, but there was no association of anti-CCP2 or anti-CCP3 with anti-CENP B, anti-Scl 70, or RF. This study confirmed the high specificity and sensitivity of both anti-CCP assays for the diagnosis of RA. The presence of anti-CCP antibodies in SSc was only correlated with the presence of arthritis.