Validation of EWALL-PI–defined risk groups across the 4 trials. UKALL14 (A-B), NILG-ALL10/07 (C-D), GIMEMA-LAL1913 (E-F) and PETHEMA-ALL-HR2011 (G-H). Panels A,C,E,G show Kaplan-Meier plots for CIR and the subdistribution hazard ratio for increased risk of relapse for patients at HR vs patients at SR. Panels B,D,F,H show the hazard ratio for OS. Patients with a EWALL-PI <2.50 were assigned to the SR group (blue lines) whereas patients at HR had EWALL-PI ≥2.50 (red lines).