Table 1 Background characteristics

Count—no.

120

68

Gender—no. (%)

 Male

32 (27)

22 (32)

0.408

 Female

88 (73)

46 (68)

Ethnicity—no. (%)

 Scandinavian

118 (98)

62 (91)

0.027

 Not Scandinavian

2 (1.7)

6 (8.8)

Age—years, mean (SD)

15.4 (1.6)

15.1 (1.6)

0.179

Body mass index—kg/m², mean (SD)

21.5 (4.2)

20.6 (3.7)

0.131

Experienced menarche (females only)—no. (%)

 No

11 (13)

5 (19)

0.411

 Yes

75 (87)

21 (81)

Days since last menstrual bleeding (females only)—median (IQR)

15 (15)

16 (14)

0.884

Disease duration—months, median (IQR)

18 (14)

n.a.

n.a.

Depressive symptom score—mean (SD)

17 (10)

6 (8)

<0.001

Fatigue score—mean (SD)

19 (6)

9 (5)

<0.001

Steps per day—mean (SD)

4662 (2386)

10,293 (3716)

<0.001

Adherence to CDC diagnostic criteria—no. (%)

 No

29 (25)

n.a.

n.a.

 Yes

88 (75)

n.a.

Adherence to Canada diagnostic criteria—no. (%)

 No

69 (60)

n.a.

n.a.

 Yes

46 (40)

n.a.