Day 19 MRD levels by flow cytometry in 3 patient cohorts defined according to day 46 MRD levels by PCR. The size of each cohort is given within the diagram. Horizontal bars represent median values. Levels of minimal residual disease (MRD) on day 19 were significantly different in the 3 groups (P < .001 by Kruskal-Wallis 1-way analysis of variance test).