Effect of self-control on health promotion behavior in patients with coronary heart disease: mediating effect of ego-depletion

ABSTRACT

The present study used a cross-sectional survey design to explore the role of ego-depletion in the relationship between self-control and health-promoting behaviors in patients with coronary heart disease (CHD). This study recruited 277 patients with CHD to measure the levels of ego-depletion, self-control and health-promotion (HP) behavior using Self-Regulatory Fatigue Scale (SRF-s), Dual-Mode of Self-Control Scale (DMSD-s) and Health Promotion Lifestyle Profile-II (HPLP-II) to examine the relationship between the three. Study found that self-control improved the patients’ HP behaviors to some extent. Self-control in patients with CHD uses ego-depletion as the mediating variable to indirectly and positively predict the level of HP behavior, and the mediating effects account for 47.76% (impulsive system) and 15.6% (control system) of the total effects, respectively.

KEYWORDS:

• Coronary heart disease
• health-promotion behavior
• ego-depletion
• self-control

Introduction

Coronary Heart Disease (CHD) has become an important risk factor that threatens the health of Chinese residents. The 2019ACC/AHA guidelines for primary prevention of cardiovascular diseases also pointed out that the total number of deaths from cardiovascular diseases accounted for the first place in the total number of deaths in China every year (Dai et al., 2019). Consequently, CHD prevention and control are of utmost importance. Poor lifestyle choices, such as smoking, drinking, lack of exercise and so on, are responsible for the increasing prevalence of CHD. Some researchers believe that the establishment of health-promotion (HP) behavior in patients with CHD is even more significant than clinical treatment (Cheng & Li, 2018; Gao et al., 2015; Nes Lise et al., 2013). HP behavior is a process of enhancing people’s ability to control their health so as to improve individual health status. In this process, people actively take some specific behaviors in order to maintain and improve their health (Hamarneh et al., 2012). According to the theory of self-control resource, after a period of tasks requiring self-control in individuals, self-control resources will be consumed. When self-control resources are seriously consumed, individuals will experience temporary depletion of self-control resources, which is named ‘ego-depletion’ (Baumeister & Vohs, 2007; Muraven & Baumeister, 2000). Previous study has revealed that ego-depletion is a common psychological experience of most patients with chronic diseases. Undergoing serious physiological and psychological stress, patients need to endure the pain caused by physical diseases, as well as regulate emotions, which rapidly depletes the patients’ self-control resources. As a result, patients often do not have enough self-control resources to manage their own health, and are unable to perform better HP behaviors (Detweiler-Bedell et al., 2008). Therefore, ego-depletion emerges as the principal cause of self-control failure and an important antecedent variable affecting HP behaviors. Other studies have found that self-control and ego-depletion are mutual cause and effect and influence each other (Martin et al., 2010; Yuan & Li, 2009). At the same time, some studies have also confirmed that relevant methods of improving self-control can be carried out from ‘open source’ and ‘throttling’, which can slow down or supplement the ego-depletion, such as supplementing glucose, constructing positive psychological resources and improving motivation (Bodenheimer et al., 2009; Fredrickson & Branigan, 2003; Gailliot, 2007; Hu et al., 2008).

In conclusion, this study hypothesized that the health promotion behavior of patients with CHD is not only affected by the self-control ability, but also by the ego-depletion mediating effect. This hypothesis was verified by the bootstrap method of AMOS21.0 statistical software. Our ultimate aim was to open up a new way for the prevention and treatment of CHD from the psychological and behavioral perspective, and to provide a new direction for disease behavior management. We also wanted to expand the application and development of ego-depletion theory in chronic disease groups.

Materials and methods

Participants

The study participants were patients with CHD which recruited from the department of cardiology of a grade III class A hospital in Chengde city, Hebei province, China, from February to July 2018 by convenient sampling. The inclusion criteria were as follows: (1) Conform to the 2015 ACC/AHA diagnostic criteria for CHD (Guang & Dai, 2016), (2) Patients who were diagnosed for the first time and their hospitalization time did not exceed 7 days (based on the requirements of the turnover rate of beds in tertiary hospitals in China), (3) Clear consciousness, accurate expression and barrier-free communication. The exclusion criteria were as follows: patients with neurological or psychiatric disorders and severe diseases of the digestive, respiratory, circulatory and endocrine systems. A total of 300 questionnaires were distributed, of which 277 were effective, and the effective rate was 92.33%.

Ethical considerations

The study was approved by the Ethical Committee of Chengde Medical University (Number: 2018007). The patients signed a written informed consent form before study.

Demographic and medical variables

We extracted the demographic information and medical variables of all of the patients from the hospital records, such as gender, age, medical payment methods, caregivers, complications and so on.

Ego-depletion questionnaire

Ego-depletion was measured by the Self-Regulatory Fatigue Scale (SRF-S). SRF-S consists of three dimensions: cognitive control, emotional control and behavior control, has 16 items, Likert rating (1 to 5 points) was used, with scores ranging from 16 to 80. The higher the score, the greater the degree of ego-depletion. Cronbach’s α = 0.84 (Nes Lise et al., 2013). In the present study, Cronbach’s α = 0.79.

Self-control questionnaire

Self-control was measured by the Dual-Mode of Self-Control Scale (DMSC-S). DMSC-S includes two systems, namely control system and impulse system. The control system consists of two dimensions: future time view, problem solving. The impulse system consists of three dimensions: easy distraction, low delay gratification, and impulsivity. Likert rating (1 to 5 points) was used. The higher the score, the better the self-control. The DMSC-S Cronbach’s α = 0.82. The control system and impulse system Cronbach’s α = 0.74 and 0.80 (Dvorak, 2009).

Health-promotion behavior questionnaire

Health-promotion behavior was measured by the Health Promotion Lifestyle Profile-II (Pender, 1987; Pender et al., 2006; Walker et al., 1987). The revised Chinese version was revised, which contains 6 dimensions and 48 items, namely: nutrition (NU), physical activity (PA), stress management (SM), interpersonal relationship (IR), spiritual growth (SG), and health responsibility (HR). Likert rating (1 to 4 points) was used, with scores ranging from 48 to 192. The higher the score, the better the HP behavior. The scoring criteria were: excellent 156–192 points, good 121–156 points, general 85–120 points, poor 48–84 points, Cronbach’s α = 0.93. (Meihan & Chung-Ngok, 2011). In this study, Cronbach’s α = 0.91, Cronbach’s range of each subscale was 0.72 ~ 0.84.

Statistical analysis

There were 23 missing data (7.67%) that were directly removed from the dataset. SPSS22.0 and AMOS21.0 statistical software were used for data analysis. Measurement data were represented by mean/standard deviation (±s). Numeric data were described in terms of frequency (n)/percentage (%). Pearson correlation analysis was used to analyze the correlation among variables. AMOS21.0 statistical software Bootstrap method was used to verify the model assumptions.

Results

Descriptive statistics

Table 1 presents the demographics and medical characteristics of patients with CHD. A total of 277 patients were included in the final data analysis, the mean age was 62.4 ± 24.5 years (range,28–78). Table 2 presents the total score and dimension score of SRF-S, DMSC-S and HPLP-II. Table 3 presents the total score of SRF-S,DMSC-S and HPLP-II and the Correlation among variables. Table 4 presents the multiple linear regression analysis of influencing factors of health promotion behavior in patient with CHD.

Table 1. The demographics and medical characteristics of participants

Demographics and medical characteristics	Sample size and proportion [n (%)]
Gender
Male	147 (53.1)
Female	130 (46.9)
Age
<40	5 (1.8)
40–49	22 (7.9)
50–69	149 (53.8)
≥70	101 (36.5)
Education
Primary school and below	40 (14.4)
Junior middle school	129 (46.6)
Technical secondary school/high school	88 (31.8)
College/University and above	30 (7.3)
Occupation
Farmer	77 (27.8)
Worker	82 (29.6)
Staff	43 (15.5)
Self-employed	24 (8.6)
Resignation/retirement	29 (16.6)
Others	22 (7.9)
Marital status
Unmarried	10 (3.6)
Married	243 (87.7)
Divorce	11 (4.0)
Widowed	13 (4.7)
Residence
City	107 (38.8)
Rural	96 (34.7)
Country	21 (7.6)
Suburban city	53 (19.1)
Per-capita family income
<1000￥	38 (13.8)
1000–3000￥	154 (55.6)
3000–5000￥	68 (24.5)
>5000￥	17 (6.1)
Medical payment method
Completely free	8 (2.9)
Employee health insurance	158 (57.0)
Resident health insurance	102 (36.8)
Own expense	9 (3.2)
Caregivers
Spouse	132 (47.7)
Child	127 (45.8)
Relatives	15 (5.4)
Care workers	3 (1.1)
Complications
No	153 (55.2)
Diabetes	61 (22.0)
Hyperlipidemia	26 (9.6)
Hypertension	33 (11.9)
Others	4 (1.4)

Table 2. Total score and dimension score of SRF-S, DMSC-S and HPLP-II (±s)

	Items	Score range	Total average score	Average score of items	Sort descending
SRF-S
Total score	16	16～80	46.34 ± 6.27	2.90 ± 0.39
Cognitive control	6	6～30	18.73 ± 3.09	3.12 ± 0.51	1
Emotional control	5	5～25	14.04 ± 4.01	2.81 ± 0.80	2
Behavior control	5	5～25	13.57 ± 2.93	2.71 ± 0.59	3
DMSC-S
Total score	21	21～105	57.71 ± 5.95	2.75 ± 0.28
Impulse system	12	12～60	31.73 ± 4.91	2.64 ± 0.37
Control system	9	9～45	25.99 ± 3.69	2.89 ± 0.41
Future time view	3	3～15	8.74 ± 1.97	2.91 ± 0.66	1
Problem solving	6	6～30	17.25 ± 2.87	2.87 ± 0.48	2
Easy distraction	3	3～15	8.36 ± 1.78	2.79 ± 0.59	3
Low delay gratification	3	3～15	7.88 ± 2.06	2.63I±0.69	4
Impulsivity	6	6～30	15.48 ± 3.02	2.58 ± 0.50	5
HPLP-II
Total score	48	48～192	111.21 ± 12.12	2.32 ± 0.25
Interpersonal relationship	8	8～32	20.81 ± 3.46	2.60 ± 0.43	1
Nutrition	9	9～36	22.08 ± 3.88	2.45 ± 0.43	2
Stress management	8	8～32	18.87 ± 3.72	2.36 ± 0.46	3
Spiritual growth	8	8～32	18.52 ± 3.79	2.31 ± 0.47	4
Health responsibility	7	7～28	14.55 ± 3.42	2.08 ± 0.49	5
Physical activity	8	8～32	16.39 ± 4.45	2.05 ± 0.56	6

Table 3. Correlation among variables

Variables	1	2	3	4
1 Health Promotion	1
2 Ego-depletion	−0.44**	1
3 Impulsive system	0.28**	−0.57**	1
4 Control system	0.25**	−0.51**	0.15**	1

Note: ** Significant correlation at .01 level (bilateral).

Table 4. Mediating effect analysis results

Dependent variable	Independent variable	R^2	ΔR^2	P	Standardized regression equation
HPB(Y)	CS(X1)	0.542	0.541	0.000	Y = 2.137X1 + 21.314
ED(M)	CS(X1)	0.374	0.371	0.000	M = −0.499X1 + 67.752
HPB(Y)	CS(X1) ED(M)	0.743	0.741	0.000	Y = 1.134X1-1.064 M + 93.391
HPB(Y)	IS(X2)	0.627	0.625	0.000	Y = 1.946X2 + 14.242
ED(M)	IS(X2)	0.584	0.583	0.000	M = −0.999X2 + 75.431
HPB(Y)	IS(X2) ED(M)	0.722	0.720	0.000	Y = 1.045X2-0.902 M + 82.267

ED, ego depletion; CS, control system; IS, impulsive system; HPB, health-promotion behavior.

Structural equation model

We analyzed the mechanisms of ego-depletion and self-control on HP behavior in patients with CHD, constructed a path analysis model based on relevant analysis results and research hypothesis, and validated the model hypothesis with AMOS 21.0 statistical software. The results of model fitting showed that:χ²/df = 1.08, RMSEA = 0.02 (P < 0.01), CFI = 0.99, GFI = 0.98, IFI = 0.97, TLI = 0.95, where all were >0.90, which in turn suggested that the model fit the data well. Effect relationships: ① Self-controlled impulse system and control system directly and negatively predicted ego-depletion. The standardized path coefficients were −0.81[95%CI(−0.57,-0.49)], −0.19[95%CI(−0.20,-0.13)]. ② ego-depletion directly and negatively predicted the levels of HP behavior. The standardized path coefficients were −0.39[95%CI(−0.39,-0.13)]. ③Self-control in patients with CHD indirectly and positively predicted the levels of HP behavior with ego-depletion as a mediation effect variable. The standardized path coefficients were −0.39*-0.81 = 0.32 (Impulsive system of self-control) and −0.39*-0.19 = 0.07 (Control system of self-control). The total effects of self-control on the level of HP behavior were as follows: 0.32 + 0.35 = 0.67 (Impulsive system of self-control) and 0.07 + 0.38 = 0.45 (Control system of self-control). The results showed that self-regulated fatigue had a mediating role in the effect of self-control on the level of health promotion behavior, and the mediating effect accounted for 47.76% and 15.6% of the total effect. The mediation model is shown in Figure 1.

Figure 1. Models of the mediation effect of ego-depletion on self-control and health-promotion behavior in patients with CHD.

Cog, cognitive; Emo, emotion; Beh, behavior; ED, ego depletion; CS, control system; IS, impulsive system; HPB, health-promotion behavior; IR, interpersonal relationship; HR, health responsibility; SM, stress management; NU, nutrition; PA, physical activity; SG, spiritual growth.

Discussion

This study found that the level of HP in patients with CHD is at medium level, which is consistent with Wang’s study (Zou, 2020), lower than that of results reported by Percival et al. (Nikki et al., 2018). The establishment of individual HP behavior is crucial for reducing the incidence of CHD and improving the patient’s prognosis, whether from the perspective of patients’ own rehabilitation or from the perspective of the implementation of clinical nursing work (Nes Lise et al., 2013). More than 50% of the occurrence of CHD is closely related to people’s poor lifestyle such as diet, exercise, smoking, alcohol abuse, and so on (EVans, 2010). Seventy five percent of the risk factors of CHD can also be attributed to the fact that individuals choose the wrong way of life and behavior (Liu et al., 2014). For these unhealthy lifestyle choices, patients with CHD need to control themselves in order to avoid ego-depletion. (Inzlicht et al., 2014). As a personality trait, self-control is an individual’s ability to self-regulate while health promotion behavior is an individual’s perception and actively generated behavior in order to maintain and improve health and realize self-worth. Therefore, self-control affects the implementation of HP behavior. Self-control includes impulse system and control system, where impulse system is more likely to lead to the lack of self-control and to unhealthy habits such as smoking, alcohol and consumption of foods high in sugar. Conversely, control system helps to resist the bad temptation and insist on healthy behaviors to achieve self-control (Liu et al., 2014). Impulse system and control system are mutually restrictive and interrelated, thus affecting the execution level of HP behavior.

This study found that the direct path test showed that self-control directly predicts HP behavior, while ego-depletion negatively predicts HP behavior. Fleig et al. have found that the enhancement of individual self-control can successfully induce their own healthy behavior, and have pointed out that ego-depletion can predict the healthy behavior in patients (Fleig et al., 2013). This study also found that patients with CHD who have relatively poor self-control ability tend to be in a state of high ego-depletion, and their HP behavior level is low. According to the theory of self-control resources, the decline of individual self-control ability is caused by the insufficiency of self-control resources. The insufficiency of self-control resources leaves patients in a state of ego-depletion (Baumeister et al., 2018; Tan et al., 2012). Nes et al. have also pointed out that ego-depletion or excessive self-depletion are common in patients with chronic diseases, which seriously affect the patients’ quality of life (Nes Lise et al., 2010). Therefore, the low level of health-promotion behavior in patients with CHD may be related to long-term ego-depletion. Ego-depletion may be a negative state of individual mental resource shortage, which leads to the individual not having enough psychological resources to carry out health promotion behaviors, such as regular medication after discharge, regular review, long-term monitoring of heart rate, blood pressure and so on.

Therefore, this study suggests that scientific and effective intervention measures can be taken to supplement their psychological resources, alleviate ego-depletion of patients, and enable patients have a high level of self-control ability to carry out health promotion behavior.

Conclusion

Patients with CHD are all in a state of ego-depletion. The interaction among ego-depletion, self-control and HP behavior is significant. Ego-depletion plays a mediating role between self-control and HP behavior.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Foundation of Educational Commission of Hebei Province of China [SD191067] and Hebei Provincial Department of Science and Technology of Technology Innovation Guidance Project-Science to Xiaomin Li.