Table 2.

Patient characteristics by their loss to follow-up status

	Missing data	Lost to follow-up (N = 41)	Not lost to follow-up (N = 49)	p value
Demographic characteristics
Age, years	2	21.0 [20.0–22.25]	21.0 [20.0–22.25]	0.42
Female sex	0	25 (61.0)	26 (53.1)	0.28
Clinical features of vascular malformation
Vascular malformation type	1			0.059
Simple venous malformation		23 (56.1)	15 (30.6)
Simple lymphatic malformation		7 (17.1)	6 (10.2)
Simple arteriovenous malformation		2 (4.9)	7 (14.3)
Combined malformation (capillary/venous/lymphatic)		6 (14.6)	14 (28.6)
Syndromic malformation		3 (7.3)	8 (16.3)
Location*	1			0.53
Head and neck/tongue		10 (24.4)	20 (40.8)
Trunk/gluteal area		10 (24.4)	12 (24.5)
Upper limb		8 (19.5)	8 (16.3)
Lower limb		18 (43.9)	18 (36.7)
Age at diagnosis	10	9.0 [0.0–13.0]	2.0 [0.0–6.5]	0.038
Previous treatment of malformation*	0			0.055
Therapeutic abstention		4 (9.8)	1 (2.0)
Sclerotherapy/embolization		18 (43.9)	24 (49.0)
General drug treatment		7 (17.1)	27 (55.0)
Physical treatment (bandages, drainage, laser)		13 (31.7)	18 (36.7)
Surgery		14 (34.2)	30 (61.2)
Follow-up procedures in the center
Age at onset of follow-up in the site	2	13.0 [9.0–14.0]	9.0 [3.5–13.0]	0.07
Type of site	0			0.71
Pediatric site		30 (73.2)	38 (77.5)
Adult site		1 (2.4)	0 (0.0)
Mixed site		10 (24.4)	11 (22.5)
Transition/change of site during follow-up (from pediatric to adult department)	1	9 (22.5)	14 (28.6)	0.23
Age at change of site	2	17.0 [16.0–16.5]	16.0 [14.5–16.5]	0.09
Average number of consultations†	7			0.08
≤ 1 time per year		11 (26.8)	25 (51.0)
> 1 time per year		30 (73.2)	24 (49.0)

Significance of bold: p < 0.05 was considered statistically significant

Results are n (%) for categorical variables and median [interquartile range] for quantitative variables

*A patient may have several characteristics

^†Mean number of consultations per year corresponding to the total number of consultations/number of years of follow-up