Expression and diagnostic utility of anti-cyclic citrullinated peptide antibodies in juvenile idiopathic arthritis

ABSTRACT

Juvenile idiopathic arthritis [JIA] is a clinically heterogeneous group of arthritis occurring in children. Anti-cyclic citrullinated peptide [anti-CCP] antibodies have been recently included in the revised diagnostic criteria for adult onset rheumatoid arthritis. Its diagnostic value in JIA is still debatable. The study is aimed to investigate the expression and diagnostic utility of anti-CCP antibodies in pediatric JIA in relationship to its various clinical phenotypes. Forty children and adolescents [13 males, 27females] with JIA as well as 35 healthy children were enrolled in this cross-sectional study. Serum anti-CCP antibodies were determined by enzymatic immunoassay and its expression was statistically correlated to clinical, laboratory, and radiological data of the patients. Anti-CCP antibodies were positive in 8 [20%] patients while not expressed in the control group. Seven out of the 8 positive cases [87.5%] had polyarticular JIA and only one patient [12.5%] had the oligoarticular onset variety. A significant positive correlation was elicited between the anti-CCP antibody levels and the number of tender joints [r= 0.39], swollen joints [0.68] and disease duration [r = 0.59]. Radiographic erosive arthritis was found in 8 patients with positive anti-CCP antibodies; 7 of whom [87.5%] suffered the polyarticular subtype and only one patient [12.5%] had the oligoarticular subtype. All the rheumatoid factor [RF] seropositive patients had positive anti-CCP antibody as well as radiographic erosive arthritis. The overall anti-CCP antibody diagnostic value in our series showed a sensitivity and specificity of 20% and 100% respectively and the positive and negative predictive values were 100%, and 52.2%, respectively. Anti-CCP antibodies have a low sensitivity but high specificity in patients with JIA with a significant relationship to clinical and radiologic severity especially in RF seropositive cases. It may thus have a diagnostic and/or prognostic utility in severe polyarticular onset disease