Background Radiographic damage was recently considered to be a feature of poor prognosis in cases of polyarticular juvenile idiopathic arthritis (pJIA). However, most radiographic studies did not differentiate pJIA from other subtypes of JIA and did not include a control group. Furthermore little is known about radiographic damages in pJIA persisting into adulthood.
Objectives To describe structural peripheral involvement in pJIA persisting into adulthood and compare observed lesions to those seen in rheumatoid arthritis (RA) using a cross-sectional observational study.
Methods All consecutive pJIA followed in a transition program were included. Age, sex, disease duration, medical or surgical treatments were collected. Laboratory tests (ESR, CRP, Rheumatoid Factor (RF) and anti-CCP) and standard radiographies of the hands and wrists, feet and hip were performed. A RA control group (<55 years), matched for sex and disease duration, was recruited. Radiographs were analyzed by two independent radiologists blinded to the diagnosis. Structural lesions on the hands and feet were assessed by the modified version of Larsen’s scoring method. The hands and feet scores range from 0 to 110 and from 0 to 50, respectively. Hips were assessed for presence of coxitis. Student and Fischer exact test were used.
Results 58pJIA (48 females/10 males) and 59 RA (52/7) were included. Respectively, mean age was 23.5±10.0 years and 43.2±9.6 years and mean disease duration 13.1±11.1 and 12.2±7.1 years. 60% and 80% were RF positive and 57% and 78% were anti-CCP positive (p=0.02). The inter-observer concordance coefficient kappa was 0.614 between the two investigators. Four pJIA patients had previous hand or feet surgery and 7 in RA group avoiding radiographs evaluation. Radiographs showed hand lesions in 41/54 (76%) pJIA and 42/50 (84%) RA-patients, feet lesions in 35/54 (65%) pJIA and 45/57 (79%) RA-patients and coxitis in 16/54 (30%) pJIA and 8/47 (17%) RA-patients (p=NS for all comparisons). Mean hands and feet scores were 17.9±21.8 and 7.7±10.8 in pJIA and 18.5±17.6 and 9.9±11.3 in RA, respectively (p=NS). Coxitis was bilateral in 13/16 (81%) in pJIA and in 2/8 (25%) of the cases of RA-patients, respectively (p=0.005).
Hand damages involved wrists, metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints in pJIA without statistical significant difference when compared to RA. RF-positive patients differed from RF-negative patients only by a shorter disease duration (10.4±9.3 vs. 17.3±12.6, p=0.02). Radiographic comparison between RF-positive and RF-negative patients revealed a higher frequency of hand damage (29/34 vs. 12/21) and less coxitis (5/31 vs. 11/23) in RF-positive subgroup (p=0.02 and 0.01, respectively). In pJIA, presence of radiographic damage correlated with a more severe disease phenotype: higher frequencies of biotherapies and surgery (p=0.009 and p=0.02, respectively), but not with RF status.
Conclusions Structural peripheral damages are frequent in young adults with pJIA and correlated with a more severe disease. A specific feature to pJIA seems to be a high risk of bilateral coxitis. This requires a particular following and monitoring of pJIA patients with unilateral hip involvement to prevent bilateralization.
Disclosure of Interest None Declared