Comparison of CD34+ precursor cell populations and time course of Hgb, RDW, CD34+ cell proportions and erythropoiesis index. (a) Concentration of circulating CD34+ precursor cells expressed as proportion of PBMCs in patients with sJIA and other JIA subtypes with or without anemia. *P < 0.05 (Student's t test). (b) Time course of individual hemoglobin concentration after the baseline sample and initiation of treatment in 12 patients with sJIA. A significant increase was noted between baseline and time points 30, 60, and 90 days (paired t test, P < 0.05). (c) Time course of individual red-cell distribution width (RDW) after the baseline sample and initiation of treatment in 12 patients with sJIA. A significant increase was seen between baseline and time points 30 and 60 days (paired t test, P < 0.05). (d) Decrease in CD34+ precursor cell proportions after initiation of treatment in 13 patients with sJIA. A significant decrease was found between baseline and time points 6 months and 12 months (t test, P < 0.05). (e) Decrease in the erythropoiesis index (geometric mean of the erythropoiesis signature expression) between baseline and 12 months later in seven patients for whom longitudinal gene-expression data were available (Signed-rank test, P < 0.05). sJIA, systemic juvenile idiopathic arthritis; non-sJIA, JIA other than sJIA; PBMCs, peripheral blood mononuclear cells; Hgb, hemoglobin; RDW, red cell distribution width.