Evaluation of the Diagnostic Utility of Second Generation Anti-cyclic Citrullinated Antibodies and Rheumatoid Factor IgM Isotype in Clinically Suspected Rheumatoid Arthritis Patients DC05-DC08
Dr. Vigneshwaran Jeyasekaran,
Flat No. 7C, Block 5, Shanthi Towers, 88 Arcot Road, Vadapalani, Chennai-600026, Tamil Nadu, India.
Introduction: Rheumatoid Arthritis (RA) is one of the most common autoimmune diseases that require early diagnosis and treatment. There are various methods by which these tests are done. The present study was carried out to compare Anti-Cyclic Citrullinated Peptide (Anti-CCP) ELISA, Rheumatoid Factor (RF) IgM ELISA and RF latex agglutination tests and their combined sensitivity and specificity in the diagnosis of RA. Usually, Anti-CCP Antibodies (Ab) appear early before RF in patients with RA. The values of these tests are given in titres. The higher the titre, the higher the chance for it to represent RA (specificity increases). Lower titres can be positive in some normal elderly patients, in other autoimmune disorders, post viral syndromes, and in some cancers.
Aim: To comparatively evaluate second generation Anti-CCP Ab with RF isotype in diagnosis of RA.
Materials and Methods: This cross-sectional descriptive study was conducted in Department of Microbiology, in a tertiary care hospital, from November 2016 to May 2018. After obtaining informed consent, blood samples were collected from 60 RA patients diagnosed using the American College of Rheumatology-European League Against Rheumatism (ACR/ EULAR) classification criteria for RA. Serum was separated and three tests were performed: RF by latex agglutination test, RF by IgM ELISA and Anti-CCP by ELISA test. The sensitivity and specificity of Anti-CCP, RF factor, RF IgM ELISA were calculated using Non-parametric tests (McNemar test) keeping the clinical diagnostic criteria as the gold standard.
Results: Among the 60 study participants, female were 51 (85%), Male/female ratio was 1:5.6. Out of 60, 39 (65%) were positive for RF by latex agglutination test. Around 41 (68.3%) were positive for RF IgM by ELISA and 42 (70%) were positive for Anti-CCP done by ELISA. Both RF ELISA and Anti-CCP had a higher sensitivity of 47.5% and 50% when compared to RF latex. Also, the specificity of Anti-CCP and RF ELISA were higher, that is 82.4% and 80.4% when compared to RF latex which had a specificity of 76.5%.
Conclusion: This study concludes and suggests that both RF IgM ELISA and Anti-CCP test should be included in the investigation panel for undifferentiated arthritis.