Ability of second-generation anti-cyclic citrullinated peptide (CCP) to predict rheumatoid arthritis in patients with early arthritis
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KeywordsPeptide Rheumatoid Arthritis Arthritis Laboratory Test Likelihood Ratio
We previously studied the diagnostic value of biological tests in RA and found that IgG-AKA, first generation of anti-CCP, IgM-RF by ELISA, and the latex test is the best combination in diagnosing RA. The goal of the present study was 1) to study the diagnostic value of the second generation of anti-CCP and 2) to determine the diagnostic value of second-generation anti-CCP used in combination in the same population.
A cohort of 270 patients with early arthritis underwent a standardized examination, laboratory tests and radiographs in 1995–1997. The final diagnosis was evaluated by a panel of five rheumatologists between June and December, 1999. The respective diagnostic values of antiperinuclear factor, antikeratin antibody, and anti-CCP (commercial kits: Eurodiagnostica first generation [EFG], Eurodiagnostica second generation [ESG], and Axis-Shield [AS]) carried out on sera taken at the patients' first visit in discriminating between patients who did (98/270; 36%) and did not have RA at the last visit was evaluated using receiving-operator characteristic curves. To evaluate the combination of anti-CCP with other laboratory tests in discriminating between patients with and without RA, a multiple logistic regression with backward selection using the likelihood ratio test was applied.
1) Anti-CCP, APF and IgG AKA were not perfectly correlated with each other. For anti-CCP EFG (cutoff 53 UI), ESG (cutoff 0.120 OD), and AS (cutoff 0.320 OD), sensitivity and specificity were 47%-93%, 57%-94% and 58%-94%, respectively. 2) By the use of a multiple logistic regression, second generation anti-CCP, IgG-AKA, the latex test and IgM-RF ELISA were selected.
ESG and AS are the best tests for predicting RA. Combining one of these tests with IgG-AKA, IgM-RF, and the latex test slightly increases the diagnostic value.