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

Objectives: Macrophage activation syndrome (MAS) is a severe complication of systemic juvenile idiopathic arthritis (SJIA). We aimed to compare the characteristics of SJIA patients who developed MAS in the disease course to those who never experienced MAS. Methods: Patients with SJIA were included. The features of the patients at the time of SJIA diagnosis were compared. Multivariate logistic regression and ROC analyses were used while evaluating factors associated with MAS. Results: Overall, 126 SJIA patients (M/F:1.17) were included. Eighty-six (68.2%) never had MAS. At the time of SJIA diagnosis, age was younger; the duration of fever was longer; rash, hepatomegaly, and splenomegaly were more frequent and arthralgia/arthritis was less common among patients who had MAS in the follow-up than those who never had MAS. Also, white blood cell, neutrophil, and platelet counts and fibrinogen were lower, while transaminases, lactate dehydrogenase, triglyceride (TG), and ferritin levels were higher among patients with MAS than those without MAS. The multivariate regression analysis disclosed age at symptom onset, duration of fever, platelet count, TG and ferritin levels as independent MAS predictors. For ferritin level/platelet count (F/P) ratio at the time of SJIA diagnosis, a threshold of ≥1.1 performed best to predict a MAS-prone disease course with a sensitivity of 90% and a specificity of 82.6%. Conclusion: 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. [ABSTRACT FROM AUTHOR]