A Study on the Importance of Anti Cyclic Cytrullinated Peptide Antibodies (Anti-CCP) and Rheumatoid Factor (RF) Assay in Detection of Patients with Rheumatoid Arthritis in North Eastern Part of India

Objective: Rheumatoid arthritis (RA) is a polyarticular and systemic chronic inflammatory autoimmune disease, occurring throughout the world. The aim of the present study is to observe the role of anti-CCP antibody and Rheumatoid Factor (RF) assay in diagnosing patients of rheumatoid arthritis in north-eastern part of India, in the state of Assam and also to evaluate the individual and combined sensitivity and specificity of anti-CCP antibody and RF assay in diagnosing RA. Methods: A total of 88 cases presenting with history of polyarthritis were included in the study of which the study group comprised of 57 clinically diagnosed cases of rheumatoid arthritis and control group comprised of 31 patients of non-RA rheumatic diseases having joint pain. Individual sensitivity and specificity of the above tests, and also the combined specificity of the two tests and also the three tests were calculated and the results of the tests were compared with each other to examine the correlation between them. Results: Sensitivity of anti-CCP ELISA, RF IgM ELISA and RF Latex test was 91.23%, 75.44% and 40.35% with specificity of 70.97%, 67.74% and 90.32% respectively. If the three tests are combined then the combined specificity of the three tests is 99.59%. One important observation was that out of 9 anti-CCP positive cases in the control group(n = 31) 5 cases were weakly positive (titer 6.25 – 20 U/ml), considering cut-off value 6.25 U/ml as mentioned by the kit.If these weakly positive cases in the control group are considered as negative, then specificity of anti-CCP ELISA increases from 70.97% to 87.1% which is more acceptable. Conclusion: From this study it is observed that anti-CCP antibodies are highly sensitive and specific for diagnosing RA. If this test is combined with RF IgM ELISA and Latex test then combined specificity can be increased more than 99%. However, weakly positive titers of anti-CCP antibodies are more prevalent in other non-RA rheumatic diseases in North-Eastern part of India.