To characterize Japanese patients having adult Still's disease (ASD) with chronic arthritis (> 6 months) and to examine the association of chronic arthritis with carpo:metacarpal ratio (CMC ratio), an index of radiographic progression in rheumatoid arthritis (RA).
Twenty-seven patients with ASD (16 women and 11 men, mean age at disease onset 27.7 years) were classified into 2 groups: patients with (chronic articular ASD, 16 patients, 59%) or without (systemic ASD, 11 patients, 41%) chronic arthritis. Clinical and laboratory findings were compared between both groups. CMC ratio was calculated on serial hand radiographs in patients with chronic articular ASD.
In our series, serositis was rarely observed in chronic articular ASD. Peripheral arthritis (including transient arthritis), such as metacarpophalangeal, proximal interphalangeal, or ankle joint, was more frequently observed in chronic articular ASD than in systemic ASD (p < 0.05). Wrist arthritis was frequently observed also in systemic ASD; however, joint space narrowing of carpometacarpal or intercarpal joints was recognized only in chronic articular ASD (44%). CMC ratio at the last observation in 14 patients with chronic articular ASD was significantly decreased (0.526 +/- 0.039) compared to that at disease onset (0.553 +/- 0.034) (p < 0.05), while no decrease was observed in 4 with systemic ASD (0.565 +/- 0.062 at disease onset, 0.563 +/- 0.043 at the last observation).
It is suggested that chronic articular ASD has certain characteristics. CMC ratio may be a quantitative index for assessment of radiographic changes of carpal joints, not only in RA but also in chronic articular ASD.