A Comparison of Anti-Cyclic Citrullinated Peptide Antibodies and Rheumatoid Factor in Diagnosis of Rheumatoid Arthritis

Abstract

Background: Conventionally, the serology test routinely used in rheumatoid arthritis (RA) is the determination of serum Rheumatoid Factor (RF), but recently anti-cyclic citrullinated peptide antibodies (anti-CCP antibodies) are also recognized as auto antibodies for the diagnosis of RA. Objective: To determine and compare the diagnostic performance of anti-CCP and RF to diagnose rheumatoid arthritis in Bangladesh. Methods: This was a cross-sectional descriptive type of study conducted in the department of Medicine, Rajshahi Medical College Hospital, Rajshahi, Bangladesh. Total 100 serum samples: 40 from definite RA patients according to the American Rheumatism Association (ARA) criteria, 30 from non RA patients and 30 samples from apparently healthy control individuals, were included in this study. IgG anti-CCP antibodies and IgM RF were determined by first-generation ELISA method and Latex agglutination method respectively. The diagnostic performance of anti-CCP and RF were determined by calculating the four indices of test validity: sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Results: Among the three study groups, anti CCP antibody was positive in 19 (47.5%) patients of RA group, none in non-RA group and only one patient in healthy group. IgM-RF was positive in case of 21 (52.50%) patients of RA group, and 3 (10%) patients of NRA group and none of control group. Sensitivity and specificity of anti CCP antibody to differentiate rheumatoid arthritis patients from non-rheumatoid arthritis patients were 47.5% and 100.0% respectively. Sensitivity and specificity were 52.5% and 90.0% in case of RF. Conclusion: The diagnostic performance of both anti-CCP and RF were not satisfactory, particularly considering sensitivity. However, anti-CCP is the better choice than RF in RA diagnosis due to the high specificity. The combination of anti-CCP and IgM-RF may yield better results in RA diagnosis than either test alone among the study population.