An anti-CCP test is a blood test that looks for CCP (cyclic citrullinated peptide) antibodies in the blood. CCP antibodies, also called anti-CCP antibodies, are a type of autoantibody that can mistakenly attack healthy tissues. This test is used to help diagnose and differentiate rheumatoid arthritis from other types of arthritis. It is often done along with or after a rheumatoid factor (RF) test. CCP antibodies provide a more accurate diagnosis of rheumatoid arthritis compared with RF testing. A positive result means that these antibodies were found in the blood, indicating the presence of rheumatoid arthritis. A negative result means that no CCP antibodies were found, but it does not rule out rheumatoid arthritis. The sensitivity of the test is low, and a negative result does not exclude the disease. The test can also predict aggressive joint erosion and establish a prognosis for the progression of the disease.