Comparative Evaluation of Rheumatoid Factor and Anti-CCP Antibody Tests as Diagnostic Markers for Rheumatoid Arthritis: A Cross-sectional Study from a Tertiary Care Centre in Dehradun, Uttarakhand, India

Introduction: Rheumatoid Arthritis (RA) is a chronic autoimmune disease with a global prevalence of approximately 1%. It is characterised by persistent joint inflammation and the production of multiple autoantibodies, leading to joint destruction, deformities, physical disability, and a reduced quality of life. Rheumatoid Factor (RF) is an antibody that targets the Fc portion of human IgG, whereas Anti-Cyclic Citrullinated Peptide (Anti-CCP) is an autoantibody generated following citrullination, often appearing in the early stages of RA. Both RF and anti-CCP are considered valuable serological markers for diagnosing RA. Aim: To evaluate RF and anti-CCP antibody tests as diagnostic markers for RA. Materials and Methods: This cross-sectional study was conducted in the Department of Microbiology, Government Doon Medical College and Hospital, Dehradun, Uttarakhand, India over a 12-month period (May 2023 to April 2024). All clinically suspected RA patients above 10 years of age were included in the study. A total of 718 serum samples from clinically suspected RA patients were collected for AntiCCP and RF testing over one year. Blood samples were collected aseptically and serum was separated for testing. RF was detected using the latex agglutination method on an automated analyser (Bio Systems Diagnostics Pvt. Ltd., Tamil Nadu, India), with values >14 IU/mL considered positive. AntiCCP antibodies were analysed using a Chemiluminescent Immunoassay (CLIA)-based Abbott Architect iSystem (Abbott Diagnostics, Illinois, USA), with values >5 IU/mL considered positive. All tests were performed according to the manufacturer’s instructions. Demographic details such as age and gender were recorded for all participants. Statistical analysis was conducted using Statistical Package for the Social Sciences (SPSS) version 23.0, with a p-value <0.05 considered statistically significant. Results: Of the 718 serum samples tested, 281 (39.1%) were positive for either Anti-CCP or RF. A total of 118 (16.4%) were Anti-CCP positive, and 109 (15.2%) were RF positive correspondingly among these samples. A total of 437 samples (60.9%) were negative for both Anti-CCP and RF. Among the 718 samples analysed, 163 (22.7%) were RF positive and AntiCCP negative, while 109 (15.2%) were positive for both AntiCCP and RF. Nine samples (1.25%) were exclusively Anti-CCP positive. Conclusion: Anti-CCP shows higher specificity and is useful in predicting disease progression, as it appears early in the course of RA. Patients who are RF seropositive but AntiCCP seronegative indicate that RF can be elevated in other autoimmune diseases, decreasing its diagnostic reliability for RA. Anti-CCP testing can aid in the early detection of RA, enabling targeted interventions that may modify disease progression and improve patient outcomes and quality of life.