Diagnostic utility of anti-citrullinated protein antibody and its comparison with rheumatoid factor in rheumatoid arthritis

To assess the diagnostic utility of anti-citrullinated protein antibody (anti-CCP) in rheumatoid arthritis (RA) and compare it with rheumatoid factor (RF). Analytical study. Section of Chemical Pathology, Department of Pathology and Microbiology and Medicine, the Aga Khan University, Karachi, from January to May 2010. A review of medical records of patients presenting to the clinics with complaints of muscular or joint pains and who were tested for their serum anti-CCP was done. Inclusion criteria were presence of clinical synovitis in at least one joint and an absence of alternative diagnosis. Patients with arthralgia alone or with missing acute phase reactants information were excluded. Scoring and classification of RA was done using the 2010 RA Classification Criteria by the American College of Rheumatology (ACR). Out of the 98 charts reviewed, ACR criteria showed 54 cases with RA. The mean age of the group was 46 ± 15 years, 82.7% being females. High titers of anti-CCP corresponded with the ACR scores. The sensitivity and specificity of anti-CCP and RF reactivity for the diagnosis of RA were 54.7% and 95.5% versus 59.3% and 88.4% respectively. Anti-CCP is useful for the diagnosis of RA due to its higher specificity as compared to RF and can predict disease severity.