Rheumatoid Arthritis (RA) is a common, systemic autoimmune disease that 0.5-1.0% of the world population is affected. RA is characterized by chronic inflammation of the synovium which can lead to progressive joint destruction, disability and mortality.
As joint damage is irreversible, early therapeutic intervention is of paramount importance for the prognosis of patients.
The most frequent serological diagnostic testing is the measurement of rheumatoid factor (RF).
The RF antibody is present in about 75% of RA patients, but its specificity is limited, as it is often present in healthy individuals and patients with other rheumatic or inflammatory diseases, autoimmune diseases or chronic infections.
Recently, new specific autoantibodies to citrullinated proteins antigens (ACPAs) have made a crucial contribution to the diagnosis of RA.
Although many assays are available to test for ACPAs to specific antigens, for the clinical management of RA, most ACPA testing is performed using a synthetic cyclic citrullinated protein (CCP) as the antigen to detect ACPAs.
An anti-CCP assay is capable to detect the autoantibodies against citrullinated proteins which have a relatively high sensitivity (reportedly between 50-75%) for rheumatoid arthritis and extremely high specificity (about 90%) for RA.
Its high specificity is why the anti-CCP test has become an important part of the diagnostic process for RA.
