Percentage of patients in each age group that experienced grade 2 or higher bleeding in each organ system. Age group comparisons with pairwise P values < .05 are noted (A: 0-5 years vs 6-12 years; B: 0-5 years vs 13-18 years; C: 0-5 years vs ≥ 19 years; D: 6-12 years vs 13-18 years; E: 6-12 years vs ≥ 19 years; F: 13-18 years vs ≥ 19 years).