Comparison of the diagnostic values in rheumatoid arthritis: Anti-CCP antibodies and other serological tests

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease. Early diagnosis, early and aggressive treatment are the best means of avoiding joint destruction, organ damage and disability. This prospective study was carried out to determine the relationship between RA and laboratory tests used in the diagnosis of RA. 199 patients (20 males, 179 females; mean age: 50.6 years) that were suspected to be RA were included in the study. Anti-CCP, RF, ESR, and CRP tests were performed for all patients. The patients were divided two groups named RA and non-RA according to American College of Rheumatology criteria. Of the all patients, 96(48.2%) tested as positive for anti-CCP antibodies. Of the RA patients, 93 (68.9%) were positive for anti-CCP antibodies. The positivity of anti-CCP antibodies was 4.7% (3/64) for non-RA. Sensitivity, specificity, PPV, and NPV in diagnosis of RA for antiCCP respectively were 0.69, 0.95, 0.97, and 0.59, and for high positive anti-CCP respectively were 0.55, 1.00, 1.00, and 0.52, and for RF respectively were 0.59, 0.92, 0.94, and 0.52, and for high positive RF respectively were 0.54, 0.98, 0.99, and 0.54, and for CRP respectively were 0.73, 0.78, 0.87, and 0.57, and for ESR respectively were 0.84, 0.30, 0.72, and 0.46. Sensitivity for the diagnosis of RA could be further increased by a combination of the anti-CCP and RF tests. There was a positive correlation between anti-CCP and RF positivity (=0.59537), anti-CCP and RF high positivity (=0.537364), ESR and CRP (=0.426544). It is concluded that performing anti-CCP test in the diagnosis of RA could be beneficial since it has high specificity and positive predictive value. If this test was performed together with RF, it may be more beneficial.