Age-related diagnostic utility of rheumatoid factor, anticyclic citrullinated peptide and antikeratin antibodies in Chinese patients with rheumatoid arthritis

Objectives: Retrospective study to evaluate the diagnostic utility of rheumatoid factor (RF), anticyclic citrullinated peptide antibodies (ACPA) and antikeratin antibodies (AKA) in a broad age range of patients with rheumatoid arthritis (RA). Methods: Clinical and serological data from patients with RA were collected and analysed. Patients were stratified according to age (< 16 years [juvenile idiopathic arthritis; JIA], 16-40 years; 41-60 years and >60 years) and sex. Results: The study included 3725 patients. There were no significant sex-related differences in rates of RF, ACPA or AKA positivity. RF, ACPA and AKA positivity were significantly less common in patients aged < 16 years than those aged >= 16 years. There were no other significant differences between age groups. Conclusions: RF, ACPA and AKA have better diagnostic value for RA in adult patients than in patients with JIA. A combination of RF, ACPA and AKA serological testing may be a useful diagnostic tool for RA in Chinese adults.