Adolescent non-suicidal self-injury: The moderating influence of social support utilization on depression

Table 1 Comparison of characteristics between the non-non-suicidal self-injury and non-suicidal self-injury groups, n (%)

Variables	Non-NSSI (n = 56)	NSSI (n = 258)	t/χ²	P value
Age, mean (SD)	14.5 (1.8)	14.1 (1.5)	2.8	0.216
Gender			12.1	0.011a
Male	20 (35.7)	38 (14.7)
Female	36 (64.3)	220 (85.3)
Only child			4.6	0.114
No	24 (42.9)	154 (59.7)
Yes	32 (57.1)	104 (40.3)
Grade			4.2	0.216
Primary	4 (7.1)	31 (12.0)
Junior	36 (64.3)	182 (70.5)
Senior	16 (28.6)	45 (17.4)
Study status			9.2	0.157
In school	17 (30.4)	42 (16.3)
Suspension	10 (17.9)	74 (28.7)
Leave	26 (46.4)	136 (52.7)
Return	2 (3.6)	5 (1.9)
Dropout	1 (1.8)	1 (0.4)
Academic performance			2.0	0.458
Top third	12 (21.4)	63 (24.4)
Middle third	35 (62.5)	136 (52.7)
Bottom third	9 (16.1)	59 (22.9)
Interpersonal relationships			7.3	0.114
Good	17 (30.4)	57 (22.1)
Average	32 (57.1)	124 (48.1)
Poor	7 (12.5)	77 (29.8)
Economic status			4.4	0.458
Much better	2 (3.6)	9 (3.5)
Better	20 (35.7)	75 (29.1)
Average	31 (55.4)	143 (55.4)
Worse	1 (1.8)	25 (9.7)
Much worse	2 (3.6)	6 (2.3)
Father's education			2.7	0.601
≤ Junior high	22 (39.3)	85 (32.9)
Senior high	11 (19.6)	75 (29.1)
College	10 (17.9)	43 (16.7)
Bachelor	10 (17.9)	47 (18.2)
≥ Master	3 (5.4)	8 (3.1)
Mother's education			4.5	0.458
≤ Junior high	22 (39.3)	98 (38.0)
Senior high	12 (21.4)	76 (29.5)
College	10 (17.9)	42 (16.3)
Bachelor	8 (14.3)	36 (14.0)
≥ Master	4 (7.1)	6 (2.3)
Childhood adversity			0.8	0.458
No	17 (30.4)	98 (38.0)
Yes	39 (69.6)	160 (62.0)

^aP < 0.05.

NSSI: Adolescents with major depressive disorder and non-suicidal self-injury group; non-NSSI: Adolescents with major depressive disorder without non-suicidal self-injury group; P values were adjusted using the FDR method. t-tests were used for continuous variables (age) and χ² tests for categorical variables. NSSI: Non-suicidal self-injury.

Table 2 Group comparison of psychological measures

Variables	Non-NSSI (n = 56)	NSSI (n = 258)	F	P values
SES (self-esteem)	24.8 (6.4)	21.1 (4.9)	24.8	< 0.001c
BIS (impulsiveness)	63.2 (10.6)	68.7 (8.8)	17.8	< 0.001c
Attentional impulsiveness	14.8 (3.5)	16.9 (3.1)	21.9	< 0.001c
Motor impulsiveness	20.2 (3.9)	21.5 (3.7)	5.2	0.025a
Non-planning impulsiveness	25.9 (5.2)	27.8 (4.4)	8.1	0.006b
SDS (depression)	27.5 (7.6)	33.2 (6.2)	37.0	< 0.001c
TSSRS (social support)	47.5 (17.8)	55.4 (15.2)	13.4	< 0.001c
Subjective support	13.8 (6.3)	16.5 (5.3)	14.3	< 0.001c
Objective support	14.6 (6.3)	17.5 (5.9)	10.7	0.002b
Support utilization	19.1 (7.4)	21.5 (6.4)	6.5	0.013a

^aP < 0.05.

^bP < 0.01.

^cP < 0.001.

NSSI: Adolescents with major depressive disorder and non-suicidal self-injury group; non-NSSI: Adolescents with major depressive disorder without non-suicidal self-injury group. Values are presented as mean (SD). F-statistics are shown for reference. P-values were obtained through permutation tests with 10000 iterations. SES: Self-esteem scale; BIS: Barratt impulsiveness scale; SDS: Self-rating depression scale; TSSRS: Teenager social support rating scale; NSSI: Non-suicidal self-injury.

Table 3 Stepwise logistic regression analysis predicting non-suicidal self-injury

Variables	β	SE	Wald	P value	OR	95%CI for OR
Depression (SDS score)	0.12	0.03	3.70	< 0.001c	1.13	[1.06, 1.21]
Education level	-0.42	0.29	-1.44	0.150	0.65	[0.37, 1.16]
Attention impulsiveness (BIS)	0.09	0.06	1.42	0.156	1.09	[0.97, 1.23]
Social support utilization (TSSRS)	-0.11	0.05	-2.04	0.041a	0.90	[0.81, 0.99]
Overall social support (TSSRS)	0.03	0.02	1.43	0.153	1.03	[0.99, 1.07]

^aP < 0.05.

^cP < 0.001.

Model χ² (5) = 41.31, P < 0.001. Nagelkerke R² = 0.203. This table presents the final model of a stepwise logistic regression. BIS: Barratt impulsiveness scale; SDS: Self-rating depression scale; TSSRS: Teenager social support rating scale.

Table 4 Hierarchical regression analysis for variables (self-rating depression scale and teenager social support rating scale) predicting non-suicidal self-injury, n = 314

Variables	Model 1	Model 2
Constant	0.822 (0.021)c	0.843 (0.023)c
SDS	0.018 (0.003)c	0.020 (0.004)c
TSSRS social support utilization	-	–0.006 (0.004)
SDS × TSSRS social support utilization	-	–0.001 (0.000)a
R²	0.102	0.118
Adjusted R²	0.099	0.109
ΔR²	-	0.016
F for ΔR²	-	3.900a

^aP < 0.05.

^cP < 0.001.

Standard errors are in parentheses. SDS: Self-rating depression scale; TSSRS: Teenager social support rating scale.

Table 5 Simple slope analysis of self-rating depression scale predicting non-suicidal self-injury at different levels of teenager social support rating scale-reported social support utilization

TSSRS-reported social support utilization	Effect	SE	P value	95%CI
M - 1 SD (14.382)	0.025	0.004	< 0.001c	[0.017, 0.033]
Mean (21.025)	0.020	0.004	< 0.001c	[0.012, 0.027]
M + 1 SD (27.669)	0.015	0.005	0.003b	[0.005, 0.024]

^bP < 0.01.

^cP < 0.001.

SDS: Self-rating depression scale; TSSRS: Teenager social support rating scale.