Original papers: clinical or basic research anti-cyclic citrullinated peptide antibodies - activity markers in rheumatoid arthritis

BACKGROUND Immunological abnormalities in rheumatoid arthritis (RA) imply several antibodies, among which anti-cyclic cytrullinated peptide antibodies (anti-CCP) have the highest sensitivity and specificity. Their diagnostic and prognostic value in RA is well known, although their value as markers of the disease activity has not been established yet. OBJECTIVES The aim of this study is to evaluate the correlation between anti-CCP antibodies and RA activity which eventually leads to the best treatment of choice. PATIENTS AND METHODS 217 consecutive patients hospitalized in the Department of Internal Medicine and Rheumatology, "Sf Maria" Clinical Hospital between 01.01-31.06 2007 were retrospectively studied. They were divided into two groups: group A-111 patients with RA (ACR criteria fulfilled) and group B-106 patients with other rheumatic diseases. The following parameters taken out of the patients files were studied: parameters of the clinical activity of disease (C reactive protein, fibrinogen), rheumatoid factor (RF) and anti-CCP antibodies. Disease activity score (DAS) using 4 variables (number of tender joints, number of swollen joints, erythrocyte sedimentation rate and assessement of the disease activity) was also studied. Data were processed with SPSS program using linear functions, Pearson correlation coefficient and Hi2 test of interdependency. RESULTS The sensitivity of anti-CCP antibodies in patients with RA was 56.75%. The specificity of anti-CCP antibodies in patients with RA was 90.56%. Low seric levels of anti-CCP antibodies were also found in patients without RA, but with other conditions like: osteoarthritis, viral polyarthritis, infectious myositis and Still disease; moderate to high seric levels were found in patients with psoriatic arthritis. Significant correlations were found between anti-CCP antibodies and DAS (r = 0.437), between anti-CCP and fibrinogen (r = 0.32) between anti-CCP antibodies and C reactive protein (r = 0.237) as well as between anti-CCP and RF (r = 0.38). CONCLUSIONS Anti-CCP antibodies are highly specific but moderately sensitive for RA, their highest frequencies and seric levels being found in seropositive RA. Anti-CCP can be used in patients with RA not only as a diagnostic marker but also as a reliable test for assessing the activity of the disease.