Anti-cyclic citrullinated peptide antibody is a good indicator for the diagnosis of rheumatoid arthritis

Objectives: Anti-cyclic citrullinated peptide (CCP) antibody has recently been used in the classification
of rheumatoid arthritis (RA). This antibody is more specific than rheumatoid factor (RF) for the diagnosis of RA. The study objectives were to determine the sensitivity, specificity, positive and negative predictive values of anti-CCP in RA diagnosis.
Methodology: Eighty RA patients and 80 non-RA individuals were included in the study. Blood was collected from both arms of study subjects and tested for anti-CCP and RF antibodies. Relevant clinical information and laboratory profiles of the RA patients were evaluated using patients’ medical records and Integrated Laboratory Management System (ILMS), respectively.
Results: The sensitivity and specificity of anti-CCP were 35% and 100% respectively. The positive and
negative predictive values were 100% and 61%, respectively. Positive anti-CCP was found significantly
associated with multiple joint pain (p < 0.001) and hand’s joints pain (p=0.01), symmetrical joints
involvement (p=0.015) and high CRP value (p < 0.001). Anti-CCP was also found to have positive association with RF (p < 0.001).
Conclusion: Anti-CCP is highly specific for the diagnosis of RA. High positive predictive value should be taken into consideration for effective treatment.
KEY WORD: Rheumatoid arthritis, anti-CCP, Rheumatoid factor, Sensitivity, Specificity, Positive predictive value, Negative predictive value.
Study site: Rheumatology Unit, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia