Background: The usefulness of anti-cyclic citrullinated peptide antibodies (anti-CCP antibodies) to identify rheumatic arthritis (RA) from other rheumatic diseases presenting with joint pain is not well studied.
Aims: We aimed to determine the sensitivity and specificity of anti-CCP antibodies in Indian RA patients with respect to non-RA rheumatic diseases and to study the relationship of anti-CCP antibodies and IgG, IgM and IgA rheumatoid factor in RA.
Settings and design: Case-control cross-sectional study carried out in the rheumatology division of All India Institute of Medical Sciences.
Materials and methods: Sixty-three patients with rheumatoid arthritis (RA) and 51 patients with non-RA rheumatic diseases having joint pain were included in the study. Sera were tested for anti-CCP antibodies (IgG) and IgA, IgM, IgG rheumatoid factor, using a commercially available enzyme-linked immunosorbent assay.
Statistical analysis: Statistical analysis was performed using SPSS statistical software version 11.5.
Results: Fifty-four of 63 RA patients (85.71%) were positive for anti-CCP antibodies. In the non-RA group, anti-CCP antibody was positive in only 5 of 51 patients (9.8%). Our study found a sensitivity of 85% and a specificity of 90.19% with regard to the use of anti-CCP antibodies assay in patients with joint pain to correctly identify RA. Anti-CCP antibodies positive patients did not have more erosive disease. IgM-RF-positive patients had more erosion when compared to the IgM-RF-negative group. Thirty-two of 57 (56.1%) IgM-RF-positive patients had erosions, while no patient (0/6 patients) had erosions in the IgM-RF-negative group (P=0.01)
Conclusion: Anti-CCP antibodies have high sensitivity and specificity for diagnosis of RA, in Indian patients. Anti-CCP antibodies positive patients did not have more erosive disease in our study.