Clinical utility of anti-carbamylated antibody in rheumatoid arthritis female patients: Emerging predictive value compared to anti-cyclic citrullinated peptide and rheumatoid factor

To evaluate the frequency of anti-carbamylated protein (anti-CarP) antibodies positivity in female rheumatoid arthritis (RA) patients; to study their association with different disease aspects clinically and radiologically and to assess their potential predictive role of RA disease compared to other autoantibodies. Fifty-one RA female patients and 44 age-matched controls were studied. Duration of morning stiffness, disease activity score (DAS28) and health assessment questionnaire (HAQ) were assessed. Laboratory investigations included acute phase reactants, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) and anti-CarP antibodies. Conventional radiography of both hands and feet was performed and assessed by a simple erosion narrowing score (SENS). All patients were evaluated by ultrasound 7 (US7) score. The mean age of patients was 46.9 ± 8.6 years with disease duration of 6.2 ± 5.3 years. Anti-CarP antibody was positive in 52% and 54.5% of patients seronegative for anti-CCP and RF respectively. RF was positive in 40 (78.4), anti-CCP was positive in 26(51%), and anti-CarP in 21 (41.2%) patients. Anti-CarP antibodies were significantly associated with radiological damage, DAS28, HAQ and acute phase reactants. The sensitivity and specificity were 41.2% and 88.6%, respectively for anti-CarP, 51% and 93.2% for anti-CCP and 78.4% and 90.9% for RF to diagnose RA. An association between anti-CarP antibody positivity and the disease activity, severity, structural damage and hence poor disease outcome has been demonstrated. Testing anti-CarP antibodies could be a useful marker for the assessment of disease activity as well as the expectation of prognosis in RA patients.