Anti-cyclic citrullinated peptide (anti-CCP) antibodies are a type of autoantibody that can be used as a diagnostic marker for rheumatoid arthritis (RA), an autoimmune disease that causes pain, swelling, and stiffness in the joints
. These autoantibodies are produced when the immune system mistakenly targets and attacks healthy tissues, leading to inflammation and damage in the joints
. The anti-CCP blood test is used to detect the presence of anti-CCP antibodies in the blood. A positive result, with a titer of 20-39 EU/mL, is considered weakly positive, while a titer of 40-59 EU/mL is moderately positive, and a titer of 60 EU/mL or more is strongly positive
. A negative result (less than 20 EU/mL) is considered normal
. The anti-CCP test is particularly useful in diagnosing RA due to its high specificity, with a sensitivity of around 35% and a specificity of 100%
. It is often used alongside the rheumatoid factor test, which is similar but less specific
. However, the sensitivity of the anti-CCP test can vary depending on the study population, with some studies showing sensitivities of 80.4% and others of 66.7%
. In summary, anti-CCP antibodies are a diagnostic marker for rheumatoid arthritis, with high specificity and sensitivity. A positive anti-CCP test result is a strong indication of RA, while a negative result does not exclude the disease
