Figure 1.

Cross‐sectional validation of galectin‐9 and CXCL10 as biomarkers for disease activity in juvenile dermatomyositis (DM) in 2 independent validation cohorts. A and B, Measurement of galectin‐9 and CXCL10 by multiplex immunoassay in serum from patients with active disease before start of treatment (group A), active disease while receiving medication (group AM), in remission while receiving medication (group RM), and in remission while not receiving medication (group R), in the external validation cohort (EVC) (n = 12 group A, n = 27 group AM, n = 28 group RM, n = 12 group R) (A) and the internal validation cohort (IVC) (n = 25 group A, n = 30 group AM, n = 16 group RM, n = 12 group R) (B). In group AM, 3 samples from 1 patient (from different time points at least 3 months apart) and 2 samples from 6 patients (from different time points 2–11 months apart) were included. Data are shown as box plots. Each box represents the interquartile range. Lines inside the boxes represent the median (log scale). Lines outside the boxes represent the 10th and 90th percentiles. Symbols represent individual patients. Multiplicity‐adjusted P values were determined by Kruskal‐Wallis test with Dunnett's post hoc test. C and D, Measurement of galectin‐9 and CXCL10 in paired samples from individual patients (regardless of treatment status) during active disease and remission, from the EVC (median time between samples 23 months) (C) and IVC (median time between samples 12 months) (D). P values were determined by Wilcoxon's matched‐pairs signed rank test. E and F, Area under the receiver operating characteristic (ROC) curves (AUCs) for diagnostic accuracy of galectin‐9, CXCL10, and creatine kinase (CK) in patients (regardless of treatment status) from the EVC (E) and IVC (F). Only patients with complete data for the specific ROC curve were included. G and H, Spearman's rank correlations of galectin‐9, CXCL10, and CK levels with Childhood Myositis Assessment Scale (CMAS) scores in the EVC (n = 79) (G) and IVC (n = 61) (H).