Is it possible to predict a disease course prone to macrophage activation syndrome at systemic juvenile idiopathic arthritis diagnosis?

The F/P ratio at the time of SJIA diagnosis may be a promising biomarker to predict MAS-prone disease course in SJIA. Determining MAS-prone patients at the time of SJIA diagnosis could assist physicians while tailoring SJIA treatment individually. Key points • Systemic juvenile idiopathic arthritis (SJIA) patients with macrophage activation syndrome (MAS) differ from SJIA patients who never have MAS, at the time of SJIA diagnosis. • It could be possible to predict a MAS-prone disease course at the time of SJIA diagnosis. • The ferritin/platelet ratio is a promising biomarker for predicting MAS-prone SJIA disease course.