Use of anti-cyclic citrullinated peptide antibodies and rheumatoid factor in diagnosis of rheumatoid arthritis in a tertiary care hospital.

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease that affects 0.5-1% of the general population and is characterized by a chronic, debilitating, and destructive form of arthritis. Rheumatoid factor (RF) is a frequently used diagnostic test for RA. Objectives: To evaluate the significance of anti-CCP and RF antibodies in RA diagnosis, to assess diagnostic utility of anti-CCP antibody for RA in relation to RF, and to assess the combined approach (anti-CCP + RF) for early prognosis of RA. Materials and Methods: 93 patients clinically suspected of RA attending Medicine OPD at ESIC (Employees State Insurance Corporation) Hospital, Bangalore, were included in the study. About 5 ml of blood was collected aseptically from clinically suspected RA patients. Serum was separated and tested for RA factor and anti-CCP antibodies. Statistical Analysis: Sensitivity, specificity, and positive predictive value were calculated using 2 × 2 table, with fixed row margins (a + b) and column margins (c + d); conventionally, disease is on top and test is on the side. Results: RA factor is positive in 12 RA patients, anti-CCP patients in 24 RA patients, combined RA and anti-CCP positive in 8 patients, sensitivity of RA factor 33.3%, anti-CCP 66.6%, and RA + Anti CCP 33.3% Specificity of RA factor 17.54%, Anti CCP 1.75%, and RA + Anti CCP 7% positive Predictive value of RA Factor 54.5%, Anti CCP 100%, and RA + Anti CCP 66.6%. Conclusions: Anti-CCP antibodies have a high sensitivity and positive predictive value, making them an excellent tool for differentiating RA from other forms of arthritis. Because of its high specificity, RF is a useful screening marker for RA diagnosis.