Table 2.

Distribution of children with ALL within the high- and low-risk assessment group and rate of symptomatic venous thrombosis in the observational cohorts

ALL population	Pilot cohort*	Validation cohort†	P (χ2 test)
Total number	465 of 552	339 of 347	.001
Score 2.5 or lower, n (%)	394 (86.4)	322 (94.9)
Score greater than 2.5, n (%)	62 (13.5)	17 (5.01)
VTE onset, d, n (%)	34 (7.5)	19 (5.9)	.41
Median (min-max)	32 (12-39)	34 (13-49)
Score 2.5 or lower, n (%)	11 (2.8)	8 (2.5)
Score greater than 2.5, n (%)	23 (37)	11 (64.7)	<.001‡

ALL indicates acute lymphoblastic leukemia; and VTE, venous thromboembolism.

^*Included BFM 90/95 and COALL 92/97.

^†Included BFM 2000 and FRALLE 2000.

^‡P value for score < 2.5 vs > 2.5.