Clinical predictors of remission in systemic juvenile idiopathic arthritis/Still's disease: insight from real-life data and the potential relevance of the 'window of opportunity'.

OBJECTIVES

To investigate potential predictors of remission and relapse in systemic juvenile idiopathic arthritis (sJIA), in a real-life clinical setting.

METHODS

An observational bicentric cohort study was conducted including patients diagnosed with sJIA between 2017 and 2022 in two tertiary paediatric hospitals.

RESULTS

64 sJIA patients were included. The time from first symptom to diagnosis (hazard ratio (HR): 0.991) and interleukin 1 (IL1) inhibitors treatment failure (HR: 0.236) resulted predictors of a longer time to achieve remission on therapy. Clinical inactive disease at month 3 (HR: 3.506) predicted a shorter interval of time to remission off medication while anti-IL1 failure (HR: 0.153) was found to be a predictor of longer time to achieve remission off medication. The presence of rash three months after onset (HR: 5.763) resulted significantly associated with a shorter time to relapse, while the male gender resulted a protective factor (HR: 0.247). IL1 inhibitors non-responder patients (15/42, 35.7%) presented a lower age (p=0.040) and a higher frequency of polyarthritis at onset (p=0.029), a non-monophasic disease course (p<0.001), a higher number of relapses (p=0.010), and a longer time to achieve remission on therapy (p<0.001).

CONCLUSIONS

A diagnostic and therapeutic delay predicts a longer time to reach remission in sJIA patients, and seems to affect the response to IL1 inhibition, according to the 'window of opportunity' hypothesis in sJIA treatment. A failure to IL1 inhibitors predicts a longer time to reach remission both on and off medications and is associated with an early polyarticular onset and non-monophasic disease course.