Anticitrullinated protein antibodies and radiological progression in juvenile idiopathic arthritis.

Objective: The aim of the study was to investigate whether determination of anticitrullinated protein antibodies (ACPA) provides predictive information on severity of disease course and joint destruction in children with juvenile idiopathic arthritis (JIA).

Methods: Sera from 74 children with JIA were examined for ACPA using the ELISA test. To assess joint destruction, plain radiographs of both hands were scored twice according to the Steinbrocker scale: at the beginning of observation and after 8.9 to 15.2 months (median 11.5 months) of the followup. Correlations between ACPA serum levels and the disease characteristics (type of JIA onset, disease activity, disease duration, radiological status) were investigated.

Results: Twenty-six out of 74 examined children with JIA (35.0%) were ACPA-positive [> 5 relative units (RU)/ml]. ACPA were present in all types of JIA onset, including 36.6% of children with early stage JIA (disease duration < 6 months). All of the IgM-rheumatoid factor (RF)-positive children with polyarticular type of JIA onset were simultaneously positive for ACPA. ACPA levels correlated positively with disease activity at the beginning of the study (rho = 0.7196; p < 0.0001) and after followup (rho = 0.2485; p = 0.0486). Disease duration did not significantly affect ACPA serum levels. ACPA levels correlated positively with radiological joint destruction in children with JIA, both at the beginning of the study (rho = 0.4599; p = 0.0004) and after the followup period (rho = 0.5523; p < 0.0001).

Conclusion: ACPA were superior to IgM-RF in diagnosing JIA and provided predictive information on severity of disease course and radiological outcome.