Table 3 Multivariable logistic regression models of cumulative effects of four syndemic factors on depression and suicidal ideation

Gender

Male

Ref

Ref

Ref

Ref

Ref

Ref

Female

1.73 (1.63–1.84)***

1.58 (1.48–1.70)***

1.74 (1.63–1.85)***

1.80(1.70–1.91)***

1.64 (1.54–1.75)***

1.84 (1.73–1.96)***

Grade

5–6

Ref

Ref

Ref

Ref

Ref

Ref

7–9

1.88 (1.72–2.05)***

2.13 (1.93–2.35)***

2.04 (1.86–2.25)***

1.33(1.23–1.43)***

1.37 (1.25–1.50)***

1.39 (1.28–1.51)***

10–12

2.09 (1.91–2.29)***

2.97 (2.68–3.30)***

2.64 (2.39–2.91)***

1.09(1.01–1.18)*

1.34 (1.22–1.47)***

1.28 (1.18–1.40)***

Family economic status(quintiles)

1

Ref

Ref

Ref

Ref

Ref

Ref

2

0.74 (0.61–0.89)**

0.76 (0.62–0.93)**

0.77 (0.63–0.93)**

0.82(0.68–0.98)*

0.85 (0.69–1.06)

0.87 (0.71–1.06)

3

0.40 (0.34–0.47)***

0.48 (0.40–0.58)***

0.50 (0.41–0.60)***

0.49(0.42–0.59)***

0.62 (0.51–0.75)***

0.64 (0.53–0.77)***

4

0.40 (0.33–0.48)***

0.46 (0.38–0.57)***

0.50 (0.41–0.61)***

0.49(0.41–0.59)***

0.59 (0.48–0.73)***

0.65 (0.53–0.79)***

5

0.42 (0.33–0.55)***

0.45 (0.34–0.60)***

0.49 (0.37–0.64)***

0.49(0.38–0.62)***

0.52 (0.40–0.69)***

0.57 (0.44–0.75)***

Father education level

Primary school or below

Ref

Ref

Ref

Ref

Ref

Ref

Middle school

0.95 (0.86–1.04)

0.96 (0.87–1.06)

0.96 (0.87–1.06)

0.95(0.87–1.04)

0.98 (0.88–1.08)

0.97 (0.89–1.07)

High school or above

1.01 (0.89–1.13)

1.02 (0.90–1.16)

1.10 (0.97–1.17)

1.01(0.91–1.13)

1.03 (0.91–1.17)

1.12 (0.99–1.26)

Mother education level

Primary school or below

Ref

Ref

Ref

Ref

Ref

Ref

Middle school

0.97 (0.89–1.05)

0.96 (0.88–1.05)

0.95 (0.87–1.03)

0.97(0.90–1.04)

0.96 (0.88–1.05)

0.95 (0.87–1.03)

High school or above

1.06 (0.95–1.19)

1.04 (0.92–1.17)

1.04 (0.93–1.17)

1.08(0.97–1.20)

1.06 (0.94–1.19)

1.06 (0.95–1.18)

Parental marital status

Married

Ref

Ref

Divorced, remarried, One or both of them died

1.30 (1.19–1.43)***

1.29 (1.18–1.41)***

Left-behind experience

No

Ref

Ref

Yes

1.17 (1.09–1.26)**

1.12 (1.05–1.20)**

Bullying victimization

No

Ref

Ref

Yes

3.19 (2.86–3.55)***

2.77 (2.49–3.09)***

Self-harm behavior

No

Ref

Ref

Yes

7.26 (6.74–7.83)***

10.77 (9.99–11.61)***

Syndemic condition

No syndemic condition

Ref

Ref

One syndemic condition

1.61 (1.47–1.77)***

1.60 (1.47–1.75)***

Two syndemic conditions

4.68 (4.24–5.18)***

5.30 (4.83–5.82)***

Three syndemic conditions

13.98 (12.08–16.19)***

15.87 (13.71–18.38)***

Four syndemic conditions

29.68 (19.77–44.56)***

30.46 (19.64–47.25)***