There are 2 autoantibody tests that can be helpful in diagnosing rheumatoid arthritis. Rheumatoid factor (RF) is the older of the two tests. Unfortunately, this test is not specific for rheumatoid arthritis and can be seen in other medical conditions such as chronic infections (endocarditis, hepatitis C) and paraproteinemias. Anti-CCP antibodies are much more specific for rheumatoid arthritis. That is these antibodies are not generally found in other conditions. We use the measurement of antibodies to aid in the diagnosis of rheumatoid arthritis and to help with determining prognosis. Individuals who have rheumatoid arthritis and these autoantibodies are more likely to have erosive disease. However, we do not use the antibody titers to determine disease activity over time. Disease activity is determined by a combination of number of tender joints, swollen joints, lab studies, and patient and physician global assessment.
About Rebecca Manno, MD, MHS
Assistant Professor of Medicine
Johns Hopkins University