Table 1 Basic socio-demographic characteristics and health related features of samples

Age

14.74 ± 1.46

–

14.74 ± 1.45

–

14.75 ± 1.47

–

Household Registration Residence^a

 Rural

–

4207 (39.35)

–

2175 (37.92)

–

2032 (41.01)

 Urban

–

6484 (60.65)

–

3561 (62.08)

–

2923 (58.99)

Being the Only Child^a

 No

–

7383 (65.89)

–

3742 (62.24)

–

3641 (70.11)

 Yes

–

3822 (34.11)

–

2270 (37.76)

–

1552 (29.89)

Grade^a

 Junior middle school

–

8579 (75.03)

–

4662 (75.89)

–

3917 (74.03)

 Senior middle school

–

2855 (24.97)

–

1481 (24.11)

–

1374 (25.97)

School residential status^a

 Board at school

–

2900 (25.74)

–

1502 (24.81)

–

1398 (26.82)

 Attend a day school

–

8365 (74.26)

–

4551 (75.19)

–

3814 (73.18)

Sexual orientation

 Heterosexual

–

4418 (38.62)

–

2767 (45.03)

–

1651 (31.18)

 Gay/Lesbian

–

653 (5.71)

–

241 (3.92)

–

412 (7.78)

 Bisexual

–

1524 (13.32)

–

628 (10.22)

–

896 (16.92)

 Reporting no sexual attraction

–

4845 (42.35)

–

2509 (40.83)

–

2336 (44.12)

Suicidal Ideation

0.093

 No

–

9749 (85.22)

–

5425 (88.28)

–

4324 (81.66)

 Yes

–

1691 (14.78)

–

720 (11.72)

–

971 (18.34)

Non-suicidal self-Harm

0.087

 No

–

10,061 (87.95)

–

5565 (90.56)

–

4496 (84.91)

 Yes

–

1379 (12.05)

–

580 (9.44)

–

799 (15.09)

Perceived cognitive deficits^a

1.23 ± 0.85

–

1.17 ± 0.86

–

1.30 ± 0.84

–

 − 0.153

Anxiety symptoms^a

0.74 ± 0.72

–

0.66 ± 0.70

–

0.82 ± 0.73

–

 − 0.233

Depression symptoms^a

0.59 ± 0.68

–

0.54 ± 0.65

–

0.65 ± 0.70

–

 − 0.167

Poor self-rated health status^a

2.09 ± 0.81

–

2.02 ± 0.83

–

2.18 ± 0.77

–

 − 0.199

School bullying victim^a

 No

–

10,549 (92.41)

–

5556 (90.68)

–

4993 (94.42)

0.070

 Yes

–

866 (7.59)

–

571 (9.32)

–

295 (5.58)

School bullying perpetrator^a

 No

–

9583 (83.77)

–

4876 (79.35)

–

4707 (88.90)

0.129

 Yes

–

1857 (16.23)

–

1269 (20.65)

–

588 (11.10)

Dietary restriction^a

0.160

 No

–

6735 (59.03)

–

4063 (66.31)

–

2672 (50.59)

 Yes

–

4674 (40.97)

–

2064 (33.69)

–

2610 (49.41)

Purging^a

0.008

 No

–

10,644 (93.69)

–

5719 (93.86)

–

4925 (93.49)

 Yes

–

717 (6.31)

–

374 (6.14)

–

343 (6.51)

Subjective Binging^a

0.061

 No

–

10,122 (88.61)

–

5325 (86.81)

–

4797 (90.70)

 Yes

–

1301 (11.39)

–

809 (13.19)

–

492 (9.30)

Binge Eating^a

0.003

 No

–

8629 (75.54)

–

4626 (75.42)

–

4003 (75.69)

 Yes

–

2794 (24.46)

–

1508 (24.58)

–

1286 (24.31)