Association between illness perception and depression in colorectal cancer patients: Chain mediating effects of self-efficacy and post-traumatic growth

Table 1 Participant characteristics and univariate analysis of depression (n = 290)

Variable	Group	n (%)	mean ± SD	F/t value	P value
Age	≤ 44	42 (14.5)	6.24 ± 4.08	15.308	< 0.001
	45-59	84 (29.0)	8.57 ± 4.86
	≥ 60	164 (56.6)	10.26 ± 4.17
Gender	Male	149 (51.4)	10.07 ±4.80	11.755	< 0.001
	Female	141 (48.6)	8.26 ± 4.15
Smoking	Yes	82 (28.3)	9.24 ± 4.67	0.18	0.893
	No	208 (71.7)	9.16 ± 4.56
Drinking	Yes	85 (29.3)	9.42 ± 4.96	0.322	0.571
	No	205 (70.7)	9.08 ± 4.42
Economic situation	Living beyond one’s means	176 (60.7)	9.27 ± 4.51	0.106	0.900
	Breaking even	85 (29.3)	9.13 ± 4.48
	Balance surplus	29 (10.0)	8.86 ± 5.39
Primary caregiver	Spouse	220 (75.9)	9.15 ± 4.50	3.493	0.016
	Parents	11 (3.8)	6.18 ± 4.33
	Children	57 (19.7)	10.12 ± 4.63
	Others	2 (0.7)	3.5 ± 4.95
Religious beliefs	Yes	12 (4.1)	7.92 ± 5.18	0.961	0.328
	No	278(95.9)	9.24 ± 4.56
Household registration	Urban	195 (67.2)	9.41 ± 4.45	1.361	0.244
	Rural	95 (32.8)	9.19 ± 4.58

Table 2 Correlations among study variables

Variable	Mean	SD	1	2	3	4
Illness perception	46.97	6.37	1
Self-efficacy	32.20	7.15	-0.479b	1
Posttraumatic growth	63.26	10.46	-0.478b	0.386b	1
Depression	9.19	4.58	0.577b	-0.597b	-0.438b	1

^bP < 0.01.

Table 3 Regression analysis of the mediation model

Predictor	Depression				Self-efficacy				Posttraumatic growth				Depression
	B	SE	t value	95%CI	B	SE	t value	95%CI	B	SE	t value	95%CI	B	SE	t value	95%CI
Age	0.384	0.333	1.153	(-3.176 to 0.972)	-2.074	0.559	-3.706c	(-3.176 to -0.972)	-1.962	0.822	-2.385a	(-3.581 to -0.342)	-0.238	0.310	-0.766	(-0.848 to 0.372)
Gender	-1.747	0.440	-3.962c	(-0.233 to 2.678)	1.222	0.739	1.652	(-0.233 to 2.678)	1.719	1.067	1.611	(-0.380 to 3.820)	-1.353	0.400	-3.380c	(-2.141 to -0.565)
Primary caregiver	0.040	0.267	0.151	(-0.179 to 1.588)	0.704	0.449	1.568	(-0.179 to 1.588)	-1.493	0.647	-2.306a	(-2.767 to -0.218)	0.148	0.244	0.610	(-0.331 to 0.629)
Illness perception	0.400	0.036	10.972c	(-0.571 to -0.330)	-0.450	0.061	-7.364c	(-0.571 to -0.330)	-0.578	0.095	-6.037c	(-0.767 to -0.389)	0.257	0.038	6.774c	(0.182 to 0.332)
Self-efficacy									0.235	0.085	2.774b	(0.068 to 0.403)	-0.243	0.032	-7.576c	(-0.307 to -0.180)
Posttraumatic growth													-0.047	0.022	-2.152a	(-0.091 to -0.004)
R	0.614				0.530				0.557				0.707
R²	0.377				0.281				0.311				0.500
F	43.285				27.836				25.589				47.185

^aP < 0.05.

^bP < 0.01.

^cP < 0.001.

CI: Confidence interval.

Table 4 Mediation effects of self-efficacy and posttraumatic growth

Path	Effect value	SE	LLCI	ULCI	Effectiveness ratio (%)
Direct effect
Illness perception to depression	0.2575	0.0380	0.1827	0.3323	64.37
Intermediary effect
Illness perception to self-efficacy to depression	0.1099	0.0231	0.0700	0.1599	27.47
Illness perception to posttraumatic growth to depression	0.0275	0.0130	0.0014	0.0537	6.80
Illness perception to self-efficacy to posttraumatic growth to depression	0.0051	0.0031	0.0001	0.0122	1.28
Total intermediation effect	0.1425	0.0242	0.0990	0.1930	35.63
Total effect	0.4000	0.0365	0.3283	0.4718	100

LLCI: Lower level of confidence interval; ULCI: Upper level of confidence interval.