# Clinical predictors of relapse and severe disease phenotype in children with non-systemic juvenile idiopathic arthritis

## TL;DR

This study identifies factors predicting relapse and severe disease in children with non-systemic juvenile idiopathic arthritis.

## Contribution

The study defines a severe disease phenotype based on multiple relapses and biologic use, and identifies specific clinical predictors.

## Key findings

- Longer disease duration, MCP involvement, and more joints at diagnosis predict relapse.
- Younger age, ankle, and TMJ involvement predict severe disease phenotype.
- Not all relapses indicate a severe disease course.

## Abstract

The aim of this study was to identify the predictors of relapse and severe disease in non-systemic juvenile idiopathic arthritis (JIA), a heterogeneous childhood disease. Patients with JIA were grouped based on relapse status, and those with ≥ 2 relapses requiring biologics were classified as severe disease phenotype. A total of 142 patients (63.4% female) were included in the study. Seventy-three patients (51.4%) experienced at least one relapse after achieving remission, who were significantly characterized by female gender, younger age at diagnosis, positive ANA test, and longer disease duration. Ankle, elbow, metacarpophalangeal (MCP), and temporomandibular joint (TMJ) involvement was more prevalent in patients who had experienced at least one relapse. Longer disease duration, higher number of joints involved at the time of diagnosis, and MCP involvement were found as independent risk factors for relapse. Twenty patients (14%) were grouped as having a severe disease phenotype, characterized by a younger age at the time of diagnosis, longer disease duration, and a higher number of joints involved throughout the disease course. Younger age at diagnosis, ankle involvement, and TMJ involvement were found to be independent risk factors for a severe disease phenotype.

Conclusion: In our study, longer disease duration, MCP joint involvement, and a higher number of joints involved at the time of diagnosis were found to be associated with relapse in non-systemic JIA patients. On the other hand, younger age at diagnosis, ankle and TMJ involvement were associated with severe disease phenotype.
What is Known:• JIA is a chronic joint disease characterized by relapses and remissions, and approximately half of patients experience at least one relapse after remission.What is New:• Multiple relapses and bDMARD requirement may define a severe disease course. Younger age, ankle, and TMJ involvement may predict severe disease course.• Relapses may occur with longer disease duration; not every relapse implies a severe disease course.

What is Known:

• JIA is a chronic joint disease characterized by relapses and remissions, and approximately half of patients experience at least one relapse after remission.

What is New:

• Multiple relapses and bDMARD requirement may define a severe disease course. Younger age, ankle, and TMJ involvement may predict severe disease course.

• Relapses may occur with longer disease duration; not every relapse implies a severe disease course.