Cumulative incidence of CNS relapse stratified by CITI risk group. Cumulative incidence of CNS relapse in training set (A) and validation set (B) is depicted by reverse Kaplan-Meier curve, stratified by CITI risk group. Reverse Kaplan-Meier curve for validation set without scaled y-axis is shown in top-left panel inset. For all Kaplan-Meier curves, hashmarks denote censored patients, and shading indicates 95% CI. Log-rank P values for trend are shown above the Kaplan-Meier curves. Cumulative risk, HRs with 95% CI, and Holm-Bonferroni adjusted P values for pairwise risk group comparisons are depicted in tables beneath Kaplan-Meier curves. Low-risk groups were used as reference values for training and validation sets.