Juvenile arthritis damage index predicts poor response to biological treatment: A prospective cohort study

Juvenile arthritis damage index (JADI) is a tool that measures the degree of aggressiveness of the juvenile idiopathic arthritis (JIA) course and assesses articular [JADI - articular damage (JADI-A)] and extraarticular [JADI - extraarticular damage (JADI-E)] damage. While aggressive JIA often requires early biologic disease-modified antirheumatic drugs (bDMARDs), the utility of JADI as a predictor of treatment response remains underexplored.

To evaluate the potential of JADI as a predictor of bDMARD treatment response in JIA patients.

This prospective study included 112 highly active non-systemic JIA biologic-naïve patients with a mean age of 12.2 ± 4.6 years and a median disease duration of 2.5 (interquartile range: 1-5) years. Their clinical and radiological assessment, juvenile arthritis disease activity score 71, JADI-A, and JADI-E, were evaluated twice: Before the biologic initiation (baseline) and 12 months after (end of study). At baseline, 50% had any damage, with 43% with articular damage and 23% with extraarticular damage.

During the study, JADI-A/JADI-E improved (33.9%/9.8%), worsened (8.9%/5.4%), or remained unchanged (57.1%/84.8%). Patients with baseline damage had higher markers of JIA activity: Polyarticular course, earlier onset age, ANA-positivity, and more active joints. Patients without initial structural damage (JADI"-") were more likely (odds ratio = 3.8, 95% confidence interval: 1.6-9.0, P < 0.004) to achieve a low degree of activity or remission (46.2%), while on biological therapy, their scores were comparable to JADI-positive (18.3%). Pre-biological joint damage according to the JADI-A index (P = 0.003), wrist (P = 0.035), elbow (P = 0.027), cervical spine limitation of motion (P = 0.051), and erosions confirmed by magnetic resonance imaging (P = 0.002), were associated with poor response to biological treatment and follow-up JIA activity.

Baseline structural damage in JIA is associated with diminished bDMARDs efficacy, increased disability, and shorter remission duration. JADI enhances conventional clinical risk stratification by facilitating timely initiation of bDMARDs, adherence to treat-to-target strategy and tailored patient care.