Table 1.

Sample demographics

	UK		Italy		Germany		Total
	Adolescents (N = 20)	Adults (N = 10)	Adolescents (N = 7)	Adults (N = 3)	Adolescents (N = 7)	Adults (N = 3)	Adolescents (N = 34)	Adults (N = 16)
Age
Mean (SD)	15.2 (1.4)	32.1 (10.1)	13.9 (2.1)	23.3 (6.85)	16.1 (0.8)	18.7 (0.47)	15.1 (1.7)	27.9 (10.2)
Range	12–17	18–47	12–17	18–33	15–17	18–19	12–17	18–47
Gender
Female n (%)	14 (70)	6 (60)	3 (43)	1 (33)	6 (86)	1 (33)	23 (68)	8 (50)
Ethnicity
White n (%)	14 (70)	7 (70)	6 (86)	3 (100)	6 (86)	2 (66)	26 (76)	12 (75)
Location
Urban n (%)	17 (85)	8 (80)	7 (100)	3 (100)	6 (86)	2 (66)	30 (88)	13 (81)
Age at diagnosis
Mean (SD)	12.6 (1.7)	17.6 (5.7)	11.9 (1.1)	14.3 (1.2)	13.0 (1.3)	14.0 (1.63)	12.5 (1.6)	16.3 (5.2)
Type of spots (currently)
Blackheads n (%)	10 (50)	9 (90)	6 (86)	3 (100)	5 (71)	1 (33)	21 (62)	13 (81)
Whiteheads n (%)	14 (70)	8 (80)	7 (100)	2 (66)	3 (43)	2 (66)	24 (71)	12 (75)
Papules n (%)	18 (90)	10 (100)	6 (86)	3 (100)	6 (86)	2 (66)	30 (88)	15 (94)
Pustules n (%)	17 (85)	7 (70)	5 (71)	3 (100)	5 (43)	3 (100)	27 (79)	13 (81)
Nodules n (%)	11 (55)	6 (60)	0 (0)	1 (33)	4 (57)	1 (33)	15 (44)	8 (50)
Cysts n (%)	3 (15)	6 (60)	4 (57)	1 (33)	1 (14)	–	8 (24)	7 (44)
Current severity
No acne n (%)	0 (0)	–	0 (0)	–	1 (14)	–	1 (3)	–
Mild n (%)	5 (25)	2 (20)	0 (0)	–	2 (29)	1 (33)	7 (21)	3 (19)
Moderate n (%)	9 (45)	3 (30)	4 (57)	2 (66)	4 (57)	2 (66)	17 (50)	7 (44)
Severe n (%)	5 (25)	4 (40)	2 (29)	1 (33)	0 (0)	–	7 (21)	5 (31)
Very severe n (%)	1 (5)	1 (10)	1 (14)	–	0 (0)	–	2 (6)	1 (6)
Severity at worst
Moderate n (%)	5 (25)	–	3 (43)	–	2 (29)	1 (33)	10 (29)	1 (6)
Severe n (%)	10 (50)	6 (60)	3 (43)	1 (33)	4 (57)	1 (33)	17 (50)	7 (44)
Very severe n (%)	5 (25)	4 (40)	1 (14)	2 (66)	1 (14)	1 (33)	7 (21)	7 (44)