Background Anti-CCP antibody testing is useful in the diagnosis and prognosis of RA. We discuss anti-CCP testing with an emphasis on diagnostic performance and prognostic capability.
Objectives There aim of the present study was to investigate the effect of long-term etanercept treatment on anti-cyclic citrullinated peptide (anti-CCP).
Methods A second generation commercially available ELISA kit (CCPlus Euro-Diagnostica) were assessed. Serum samples from 31 consecutive patients with refractory RA and with positive anti-CCP test were prospectively followed during etanercept and methotrexate therapy. Autoantibodies were tested at baseline and after 6, 12 and 18 months. Before therapy, at baseline, positive anti-cyclic citrullinated peptide (anti-CCP2) test were found in 100% of patients. The proportion of patients who were positive for rheumatoid factor at baseline and after 18 months was 87.1% and 74.2% respectively.
Results Median values of the Disease Activity score (DAS) significantly decreased from 4.1 (3.8 - 4.4) at baseline, to 3.8 (3.6 - 3.9), 3.2 (3.0 - 3.4) and 2.6 (3.3 - 2.4), after 6, 12 and 18 months (p<0.001) respectively. Serum anti-CCP antibody titer at baseline was 821.39 IU/ml, and the titers for 6,12 and 18 months were 784.58, 875.61, 884.62 IU/ml respectively. Anti-CCP antibody titers exhibited a no significant reduction at 6, 12 and 18 months compared to baseline (p>0,05). Significant reduction in anti-CCP antibody titer was noted only in 6 patients.
Conclusions Despite therapy with etanercept and the persistence of significant clinical improvement as indicated by DAS, no decrease of the anti-CCP antibody titers was observed. The elevated anti-CCP antibodies retain very high during treatment of RA with etanercept.
Disclosure of Interest None Declared