Clinical Utility of Rheumatoid Factor and Anti-Cyclic Citrullinated Peptide Antibody in the Diagnosis and Evaluation of Disease Activity in Patients of Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA), a chronic systemic inflammatory disease affects around 0.75% of adult Indian population and is characterized by multiple deformities. Diagnosis of RA is primarily based on clinical manifestations and serological evidence, with rheumatoid factor (RF) being the serological marker tested the most. The diagnostic specificity of RF in RA is poor as it is found in other rheumatic and non-rheumatic diseases. Anticyclic citrullinated peptide antibodies (Anti-CCP) are a better diagnostic and prognostic marker for RA, in contrast to RF, because of their early presence and high specificity. Methods: The present study was conducted in the Department of Microbiology and Department of Rheumatology Government Medical College and Hospital Srinagar from January 2017 to December 2017 where in a total of 300 patients with clinical features suggestive of RA were included. Anti-CCP antibody, RF, and C-Reactive Protein (CRP) levels were estimated in all these patients. Results: On the basis of clinical evaluation and serological evidence, 216 (72%) patients were diagnosed as cases of RA and 84 (28%) were classified as having other non-rheumatoid disorder Females represented majority of the patients. Anti-CCP antibody, RF and CRP reactivity were significantly more in RA patients. The sensitivity and specificity of anti-CCP antibody and RF were found to be 60.65% & 96.43% and 49.07% & 76.19% respectively. Conclusions: Anti-CCP antibodies are a highly specific marker for RA in our patient population making it a good modality in patients with early disease, in whom a timely diagnosis is most needed. The low sensitivity of the test indicates that a negative anti-CCP antibody test does not exclude disease, but its high specificity means that a positive result markedly increases the probability that the patient will have RA. Thus, anti-CCP testing is a must in patients suspected of having RA to aid in early diagnosis.