Baseline clinical features predicting macrophage activation syndrome in patients with systemic adult-onset Still's disease receiving interleukin-6 inhibitor treatment.

We identified baseline laboratory features associated with MAS development after initiating an IL-6 inhibitor in refractory systemic AOSD patients. These features may reflect the suppression of IL-6 signaling, and further suppression of IL-6 signaling might trigger early-onset MAS.