Radiographic damage was recently identified as a feature of poor prognosis in polyarticular juvenile idiopathic arthritis (pJIA). However, most radiographic studies did not differentiate pJIA from other subtypes of JIA and little is known about pJIA persisting into adulthood. We describe radiological peripheral involvement in young adults with pJIA compared to patients with rheumatoid arthritis (RA).
All consecutive patients with pJIA followed in a transition program were included. Age, sex, disease duration, and medical or surgical treatment information was collected. Laboratory tests and standard radiographs of the hands and wrists, feet, and hips were analyzed by 2 independent radiologists blinded to the diagnosis. One RA control group (age < 55 yrs), matched for sex and disease duration, was recruited.
Forty-three patients with pJIA and 59 with RA were included. Radiographs showed hand lesions in 79% of pJIA and 86% of patients with RA, feet lesions in 74% of pJIA and 80% of patients with RA, and hip damage in 35% of pJIA and 17% of patients with RA (p = nonsignificant). Specific to the juvenile forms were lower frequency of proximal interphalangeal joint involvement (51% vs 76%; p = 0.03) and higher risk of bilateral hip damage (86% vs 25%; p < 0.01) than in adult RA.
Structural peripheral damage is as common and as severe in young adults with pJIA as in adults with RA. The main specific feature of pJIA seems to be a high risk of bilateral hip damage. This requires a particular monitoring of pJIA patients with unilateral hip involvement to detect bilateralization.