Social Support and Self-Efficacy as Mediating Factors Affecting the Association Between Depression and Medication Adherence in Older Patients with Coronary Heart Disease: A Multiple Mediator Model with a Cross-Sectional Study

Figures & data

Figure 1 The hypothesized serial mediating model of social support and self-efficacy between depression and medication adherence. Independent variable: depression, mediating variables: social support and self-efficacy, dependent variable: medication adherence.

Table 1 Sample Socio-Demographic and Clinical Characteristics (N=238)

	N	%/ Mean±SD
Age(60~87)	238	70.5±6.40
Gender
Male	134	56.30
Female	104	43.70
Marital status
Married or with life partner	207	86.97
Single(includes divorced, widowed, separated)	31	13.03
Education attainment
Primary school or lower	98	41.18
Junior high school	81	34.03
Senior high school or higher	59	24.79
Income monthly per person RMB (USD)
<3000 (471)	168	70.59
≥3000 (471)	70	29.41
Family history of CHD
Yes	86	36.13
No	152	63.87
Co-morbidity
Yes	227	95.38
No	11	4.62
Duration of CHD
<1 year	21	8.82
1~5 years	79	33.20
5~10 years	67	28.15
≥10 years	71	29.83

Abbreviations: SD, standard deviation; CHD, coronary heart disease.

Table 2 Descriptive Statistics and Correlations Among the Depression, Social Support, Self-Efficacy and Medication Adherence (N=238)

Variables	Range	Mean±SD	1	2	3	4
			r(P)	r(P)	r(P)	r(P)
1.Depression	0–27	3.26±3.60	1
2.Social support	12–66	39.47±5.24	− 0.146 (0.025)	1
3.Self-efficacy	13–39	35.71±4.25	−0.212 (0.001)	0.344 (<0.001)	1
4.Medication adherence	0–18	14.77±3.08	−0.214 (0.001)	0.366 (<0.001)	0.573 (<0.001)	1

Table 3 Associations of Demographic, Clinical and Other Variables and Medication Adherence Among Older CHD Patients (N=238)

	Model without Social Support and Self-Efficacy			Model with Social Support and Self-Efficacy
	Coefficient^a	SE	p value	Coefficient^a	SE	p value
Self-efficacy	-	-	-	0.491	0.042	<0.001
Social support	-	-	-	0.191	0.036	0.002
Depression	−0.210	0.055	0.001	−0.085	0.047	0.118
Age	−0.028	0.033	0.685	0.031	0.027	0.590
Gender	−0.044	0.421	0.519	−0.075	0.350	0.183
Marital status	0.035	0.641	0.622	0.033	0.548	0.581
Education attainment	−0.003	0.284	0.972	−0.051	0.234	0.404
Income	0.176	0.481	0.014	0.105	0.403	0.079
Family history of CHD	−0.063	0.419	0.335	0.022	0.348	0.681
Co-morbidity	−0.002	0.940	0.979	−0.057	0.776	0.285
Duration of CHD	0.007	0.209	0.915	−0.013	0.172	0.817

Note: ^aStandardized coefficients.

Abbreviation: SE, standard error.

Table 4 Mediation Analysis of Depression and Medication Adherence (N=238)

	Effect	SE	95% CI	%*
Direct effect: Depression-medication adherence	−0.073	0.047	(−0.165, 0.019)	40.78%
Total indirect effect	−0.106	0.036	(−0.187, −0.046)	59.22%
Depression-social support-medication adherence	−0.020	0.013	(−0.056, −0.002)	11.17%
Depression-social support-self-efficacy-medication adherence	−0.018	0.012	(−0.050, −0.001)	10. 06%
Depression-self-efficacy-medication adherence	−0.068	0.035	(−0.143, −0.002)	37.99%
Total effect	−0.179	0.055	(−0.288, −0.070)	100%

Note: *The percentage of effect/total effect.

Abbreviations: CI, confidence interval; SE, standard error.

Figure 2 Result of multiple mediator model. The numbers are standardized coefficients. −0.179=standardized coefficient before introducing social support and self-efficacy into the model; −0.073=standardized coefficients after introducing social support and self-efficacy into the model. The mediation model was adjusted for the following covariates: age, gender, marital status, education, income, family history of CHD, co-morbidity, duration of CHD. *P<0.05, **P<0.01, ***P<0.001.