Correlation of FSTL-1 with serum markers of inflammation in patients with sJIA, including sIL-2Rα (A, B), ferritin (C, D), and ESR (E, F). Left-side panels represent all patient samples at all timepoints (including MAS); right-side panels represent only the MAS subset. R values are uncorrected for presence of correlation between dependent data; p values were corrected through generalized estimating equations. FSTL-1: Follistatin-like protein 1; sJIA: systemic juvenile idiopathic arthritis; MAS: macrophage activation syndrome; ESR: erythrocyte sedimentation rate; sIL-2Rα: soluble interleukin-2 receptor-α.