Table 1

Demographic information for patients with and without postoperative VTE

Variables	Total		No VTE		VTE		P value*
	n=361 384		n=361 006 (99.90%)		n=378 (0.10%)
	n	%	n	%	n	%
Age, years (mean±SD)	7.39±5.69		7.39±5.69		7.27±6.77		<0.001
≤1	71 227	19.71	71 107	19.70	120	31.75
2–5	77 789	21.53	77 720	21.53	69	18.25
6–10	81 015	22.42	80 980	22.43	35	9.26
11–15	85 333	23.61	85 263	23.62	70	18.52
16–18	46 020	12.73	45 936	12.72	84	22.22
Sex							0.414
Male	205 424	56.89	205 217	56.85	207	54.76
Female	155 960	43.19	155 789	43.15	171	45.24
ASA class							<0.001
I	116 379	32.23	116 369	32.23	10	2.65
II	156 319	43.29	156 247	43.28	72	19.05
III	79 763	22.09	79 568	22.04	195	51.59
IV	8537	2.36	8446	2.34	91	24.07
V	386	0.11	376	0.10	10	2.65

*χ² test comparing patients with and without VTE. Bolding indicates statistical significance at p<0.017 (Bonferroni correction).
ASA, American Society of Anesthesiologists; VTE, venous thromboembolism.