A CCP test may be ordered along with or following a Rheumatoid factor (RF) test to help diagnose Rheumatoid arthritis (RA). CCP may also be ordered to help evaluate the likely development of RA in patients with undifferentiated arthritis – those whose symptoms suggest but do not yet meet the ACR criteria for RA. According to American College of Rheumatology, approximately 95% of patients with a positive CCP will develop RA in the future.

CCP is primarily ordered along with an RF test when a patient has previously undiagnosed inflammatory arthritis or has been diagnosed with undifferentiated arthritis. It may be ordered as a follow-up test to a negative RF test when clinical signs, such as symmetrical joint pain and inflammation, lead the doctor to suspect RA.

As a rule, test results outside the context of clinical signs and symptoms cannot be judged. Nonetheless, when patients are positive for both CCP and RF, it is very likely that they have RA and it is likely that they may develop a more severe form of the disease. When patients are positive for CCP but not RF and clinical signs suggest RA, then it is likely that they have early RA or that they will develop RA in the future.

When patients are negative for CCP but have a positive RF, then the clinical signs and symptoms are more vital in determining whether they have RA or some other inflammatory condition. When patients are negative for both CCP and RF, then it is less likely that they have RA. It must be emphasized, however, that RA is a clinical diagnosis and may be made in the absence of positive autoantibodies.

The CCP test is promising and becoming more widely used; however, its ultimate clinical usefulness and the ways in which it will be used have yet to be fully determined.