Improved disease course associated with early initiation of biologics in untreated polyarticular Juvenile Idiopathic Arthritis: A trajectory analysis of the STOP-JIA study

Objective: To investigate the effects of early introduction of biologic disease-modifying antirheumatic drugs (bDMARDs) on disease course in untreated polyarticular JIA (pJIA).

Methods: We analyzed data of pJIA subjects participating in the Start Time Optimization of Biologics in Polyarticular JIA study (STOP-JIA; n=400) and a comparator cohort (n=248) from the Childhood Arthritis and Rheumatology Research Alliance Registry. Latent class trajectory modeling (LCTM) was applied to identify subgroups of subjects with distinct disease course based on disease activity (clinical Juvenile Arthritis Disease Activity Score) over 12 months from baseline.

Results: 198 (49.5%) STOP-JIA subjects received bDMARDs within 3 months of baseline assessment. LCTM analyses generated 3 latent classes representing 3 distinct disease trajectories, characterized by slow, moderate, or rapid disease activity improvement over time. Subjects in the “rapid improvement” trajectory attained inactive disease within 6 months from baseline. Odds of being in the rapid improvement trajectory versus the slow improvement trajectory was 3.6 times as high (95% CI 1.32-10.0; p=0.013) for those treated with bDMARDs ≤3 months from baseline compared with subjects who started bDMARDs >3 months after baseline, after adjusting for demographics, clinical attributes, and baseline disease activity. Shorter disease duration at first rheumatology visit approached statistical significance as a predictor of favorable trajectory without bDMARD treatment.

Conclusion: Starting bDMARDs within 3 months of baseline assessment is associated with more rapid achievement of inactive disease in subjects with untreated pJIA. These results demonstrate the utility of trajectory analysis of disease course as a method for determining treatment efficacy.