RESEARCH Anti-Cyclic Citrullinated Peptide Antibody Assay Effective RA Screen

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Anti-Cyclic Citrullinated Peptide Antibody Assay Effective RA Screen

NEW YORK (Reuters Health) Sept 15 - The highly specific anti-cyclic

citrullinated peptide antibody (CCP) assay provides useful additional

information in the diagnosis of rheumatoid arthritis, according to a report

in the September ls of the Rheumatic Diseases.

The first generation of the CCP assay has been shown to provide high

specificity in the diagnosis of rheumatoid arthritis, the authors explain.

" Our study is one of the first to be published using the second generation

test, CCP2. "

Dr. Inka Vallbracht of University of Munich, Germany and colleagues

prospectively evaluated the additional diagnostic and clinical value of CCP2

in 295 patients with rheumatoid arthritis, 163 patients with degenerative or

other inflammatory joint disease, 103 patients with connective tissue

disease or vasculitis, and 154 healthy controls.

The CCP2 assay provided the best specificity for detecting rheumatoid

arthritis (97.1%), the authors report, and the highest sensitivity was

obtained with the IgM-RF (rheumatoid factor) assay (66.4%). The sensitivity

of the CCP2 assay was 64.4%.

Based on a receiver operating characteristic analysis, the CCP2 assay had

the highest diagnostic value, followed by IgM-RF, IgA-RF, and IgG-RF assays.

The CCP2 assay was also positive in 30 of 87 rheumatoid arthritis patients

in whom all three RF isotypes were negative, the researchers note. Overall,

12.9% of the rheumatoid arthritis patients were IgM-RF-negative but

CCP2-positive.

Among patients with rheumatoid arthritis of less than 1 year's duration,

14.4% were CCP2-positive but negative for all three RF isotypes.

A higher percentage of patients with high disease activity (81.4%) were

CCP2-positive than patients with low disease activity (58.5%), the

investigators report, and patients with severe joint destruction were more

often CCP-2 positive (80.3%) than were patients with minimal joint damage

(54.1%).

" ELISA for IgM-RF is still most useful as a screening marker in the

diagnosis of rheumatoid arthritis, " the researchers write. " However, the

second generation CCP ELISA now has a comparable sensitivity, and in

addition it has proved to be the most specific marker for the disease. "

" We would recommend the use of CCP in all suspected RA patients, not only in

RF negative ones, " Dr. Vallbracht told Reuters Health.

" The presence of CCP (especially high levels) may indicate a more aggressive

therapy regime [is indicated] right in the beginning of the disease, " Dr.

Vallbracht added.

Ann Rheum Dis 2004;63:1079-1084.

http://www.medscape.com/viewarticle/489323