Longitudinal Assessment of the Juvenile Systemic Sclerosis Severity Score: Application in the National Registry for...

Juvenile-onset systemic sclerosis (jSSc) is a rare, heterogeneous pediatric autoimmune disease. Existing severity tools are often adapted from adult systemic sclerosis and lack pediatric-specific validation. The Juvenile Systemic Sclerosis Severity Score (J4S) was developed to address this gap by capturing multiorgan disease burden. This study evaluated the clinical use of the J4S using data from the National Registry for Childhood Onset Scleroderma (NRCOS).

We applied the J4S to 58 patients in the NRCOS cohort, analyzing scores at baseline and at one-, two-, and three-year follow-ups. Subdomain scores were assessed to evaluate organ-specific trends. An exploratory version with equal domain weighting was also tested for sensitivity.

At baseline, the mean J4S was 8.18 (±3.64), with respiratory involvement as the primary contributor. Although no significant change in total scores was observed at one (P = 0.264) or two years (P = 0.06), domain-specific improvements were noted, particularly in the skin, vascular, gastrointestinal, and musculoskeletal systems. By three years, total scores declined significantly (P = 0.028). Two patients experienced sharp score increases due to respiratory decline; one patient died during the study. The exploratory equal-weight scoring approach improved sensitivity to change and identified significant declines at each time point.

The J4S is a valuable longitudinal tool for tracking disease severity and organ involvement in jSSc. It can identify both stable and progressive disease and may help detect patients at risk for poor outcomes. Modifying domain weighting may enhance responsiveness. Future multicenter validation and clinical trial integration are warranted.