Cardiovascular diseases are among the top three causes of mortality and disability in the world [1]. Along with increase in life expectancy, an increase in prevalence of chronic diseases has taken place and death rate due to heart diseases crossed 25% line in the late 20th century and this figure is expected to be at 35-60% range by 2025. In addition, along with changes in lifestyle, non-communicable diseases have become the main cause of mortality [2]. Although the risk of communicable diseases is more because of their contagious nature, the side effects of chronic diseases including CVDs are more resilient, expensive, and debilitating [1]. Studies have shown that CVDs are among the top and most common causes of death in Iran [3]. The most common type of CVD is MI, which is the outcome of coronary vessels occlusion and ischaemia of myocardium [4]. MI is a major cause of mortality among heart patients. One MI happens in the USA every 20 second and every minute one dies due to this disease [5]. It is one of the main reasons for hospitalisation of heart patients, which is usually assumed as a threatening situation for the patient and the family [6]. According to The World Health Organization (WHO), 31% of global mortality rate in the world in 2012 was due to CVDs. According to the latest statistics by WHO, more than 75% of CVDs happen in countries with low and average income levels. Forecasts indicate that by 2020, CVDs will be the cause of more than 75% of deaths in the world. With the current trend, 4.23 million will die by 2030 due to CVDs [7,8]. Several risk factors like diabetes, hypertension, high cholesterol and lipid, and lack of adequate physical activity are effective on development and progression of CVDs [9]. As suggested by studies, most of the risk factors of CVDs are rooted in one’s behaviour and awareness [10]. In light of this, educational program scan have a notable effect on decreasing the behaviours pertinent to risk behaviour and increasing healthy behaviours [11-13]. Educational program is a key tool to change lifestyle, which is an element of health care services. In general, educational intervention is clearly an economic strategy so that each dollar spent on education results in 3 to 4 dollars saving [14]. To control the risk of CVDs and its side-effects, a healthy lifestyle is recommended, which must be featured with healthy diet, weight control and physical activity [15]. Providing access to the information about lifestyle adjustment using proper educational methods and effectiveness of a health education program, depends, to a great extent, on utilisation of a suitable education theory [16]. TPB is most comprehensive and suitable theories of studying behaviour. [17]. It takes the individual as a rational doer so that one tends to process information before showing behaviour and it is possible to change one’s fundamental beliefs and behaviours consequently [18]. As the theory implies, the main cause of behaviour is the intention to do it and the intention is a function of three factors: 1) attitudes; 2) subjective norms; and 3) perceived behaviour control in terms of ease or hardship. On the basis of this theory, individuals sometimes evaluate their behaviour positively and they intend to do so, as they tend to believe that influential and important people behave in the same way and thus their behaviour can also be controlled [18]. It is argued that this educational mode, potentially, is a way to develop behaviour change interventions for habitual behaviours in particular [19].
On one hand, lifestyle of Iranian population is not healthy in terms of CVDs, and on the other hand, along with high mortality rate, CVDs are heavy financial burden for health sectors of countries. Currently, more than one half of public health-treatment budget in Iran is spent on CVDs [20]. This indicates the necessity that CVD patients need to have self-care activities and receive required education on changing lifestyle. TPB has been applied by other studies on low-salt diet for diabetic patients [21], changing lifestyle of MI patients [22], physical exercise in heart patients [23] and physical exercise in Bariatric Surgery [24]. Thereby, applying TPB can be effective on changing lifestyle of patients with MI and the present study is an attempt to use the theory to change lifestyle of these patients in Iran.
Material and Methods
The study was carried out at two stages; at first, a cross-sectional study was carried out to determine predictors of TPB on 175 patients with MI. Constructs of attitudes, subjective norms, and perceived behaviour control predict intention to change lifestyle in the MI patients. Then, a quasi-experimental study was conducted in Fasa, Fars, Iran from June 2016 to May 2017. Based on the following formula, number of subjects in each group (control and experiment) was obtained equal to 34 and taking into account probable leaves, 50 subjects were selected for each group.
2n [(Z1-α/2 + Z1-β)2 (σ1 – σ22)/(μ1 + μ1)2
n= sample size
α=0.05
β=0.20
σ1= 2.59 in Karimi et al study [22].
σ2=1.23 In Karimi et al. study [22].
μ1=11.28 In Karimi et al. study [22].
μ2=14.03 In Karimi et al. study [22].
Level of confidence =99%
Test power = 95%
Inclusion criteria were definite diagnosis of MI by a cardiologist, participation in the educational course, no psychological disorder, age range 30-65, MI in the last year, discharged from hospital for more than three months, and not a member of health personnel. Exclusion criterion was the absence of more than one session of the participants at the training sessions. To select candidate subjects, medical files of all the MI patients hospitalized in Valiasr Hospital of Fasa City in the past year, not including the last three months were examined. The files that met the inclusion criteria were arranged based on the admittance date. Based on random number table, 100 patients were selected and then the patients with odd numbers were categorized as experiment group and the remaining in the list were categorized as control group. Given that all the patients had been discharged from the hospital at least three month prior, the authors had to visit them at their provided address and introduce them to the study. In any case if the subject was not interested, a new candidate was elected randomly. Those interested in participation were asked to sign an informed letter of consent. Data gathering tool was a questionnaire with three sections: 1) demographics (age, gender, education, job, marital status and smoking habits); 2) standard lifestyle inventory questionnaire; and 3) author-designed questionnaire based on TPB. Lifestyle inventory consists of 52 statements designed based on Likert’s four-point scores (1= never, 4=always). Different aspects of lifestyle including responsiveness, nutrition, physical activity, stress management, spiritual development, and interpersonal relationship were measured. Score range of the inventory is 52-208 and its validity and reliability have been supported by previous studies [22,25]. The questionnaire designed based on TPB was based on Ajzen’s recommended process; so that, after literature review, a quasi-structured interview was carried out with 20 MI patients – which were excluded from the main study- to extract that key attitudes. Validity of the designed questionnaire was determined through content validity so that the questionnaire was provided to 12 health education, heart, and nursing professors and their feedbacks were used to modify the questionnaire {Content Validity Index (CVI)=0.78, Content Validity Ratio (CVR)=0.58}. Reliability of the questionnaire was examined through internal consistency (Cronbach’s alpha) and test-retest method; so that the questionnaire was tested on a small group of patients with similar conditions (n=20). Cronbach’s alpha for different sections of the questionnaire was obtained at 0.75-0.95 range, which is acceptable from statistical point of view. To implement test-retest method, the same subjects were asked to fill out the questionnaire once more 15 days later and then cluster internal correlation was obtained. Correlation coefficient test for constructs of TPB was higher than 0.7 so that all the variables of the theory had acceptable consistency coefficients. The author-designed questionnaire consisted of 71 questions with four subscales designed based on Likert’s five-point scale (1-5); 21 questions on attitudes (min score=13; max score =225), 18 questions on subjective norms (min score =9; max score = 225); 22 questions on perceived behaviour control (min score = 5; max score = 15); and 10 questions on behaviour (min score = 10; max score = 50). Scoring method followed Ajzen’s proposed method; all items were reported as percentage. The questionnaires were filled out through interview once before the intervention and once three months after the intervention. Contents of the educational intervention were determined based on analysing the data obtained before the intervention and literature review including mortality rate of heart diseases in Iran and the world; function of the heart and MI in Iran and the world; symptoms and risk factors of MI (age, gender, smoking, obesity, hypertension, lack of physical activity, diabetes, unhealthy nutrition, alcohol use, and stress); healthy cooking methods; improving diet at work; weight loss methods; good effects of physical activity and exercising on the body; effects of exercising on MI; stress and managing it; heart rehabilitation; role of attitudes and beliefs in improving lifestyle; role of the others in improving lifestyle; and obstacles and facilitators found in the society to improve healthy lifestyle. The educational intervention was carried out in eight sessions (One session is of 55-60 minutes) and was focused on the constructs of TPB. To facilitate group discussion, the subjects in the intervention group were grouped in five groups of 10. Each group had its separate class time, while the contents were the same. The classes were held once a week and educations on nutrition were provided by nutritionist. Healthy lifestyle was educated through group discussion, using educational movies, role playing, and answering questions about common beliefs about the healthy lifestyle. The discussions were directed by the educator to highlight positive beliefs and attitudes of the subjects; so that the subjects would be motivated indirectly to adopt a healthy lifestyle and prepare to change their attitudes.
To improve subjective norms, the patients were asked to attend the classes with one of their family members. One session was held by a cardiologist. To change perceived behaviour control about facilitators of improving lifestyle, group discussion method was adopted, where the subjects were also taught about step-by-step changes toward adopting a healthy lifestyle. In each session, the subjects were provided with approaches to heighten their will to change a specific part of their lifestyle. The control group received no educational intervention except the standard education given by nurses when the patient is discharged from the hospital. In observance of moral concerns and after the study, a one-session healthy lifestyle class was held for the patients in the control group and they were provided with an educational booklet and a CD and one weekly educational SMS. The research plan was approved by research council of Fasa University of Medical Sciences. The collected data was analysed in SPSS 22 using logistic regression, paired sample t-test, independent t-test, and chi-squared test (p=95%).
Results
[Table/Fig-1] lists the results of logistic regression analysis for predicting intention to change lifestyle in the subjects based on programmed TPB. As the findings show, the three constructs attitudes, subjective norms, and perceived behaviour control predict intention to change lifestyle in the MI patients. Totally, the variables predict 39.6% of intention to change behaviours.
The factors effective on intention to change lifestyle in myocardial infarction patients based on Theory of Planned Behaviour (TPB).
| Variables | Beta | B | p | Dependent variable |
|---|
| Attitudes | 0. 143 | 0. 366 | 0. 021 | Intention to change lifestyle in the patients with MIR2=0.396R2Adjusted=0.023 |
| Perceived behaviour control | 0. 256 | 0. 274 | 0. 031 |
| Subjective norms | 134/0 | 0. 169 | 0. 008 |
In the quasi-experimental study, mean age of the subjects in the experiment and control groups were 52.80±6.71 and 51.65±6.90 years respectively; hence, there is no significant difference in this regard.
Analysis of the results of the intervention study using chi-squared test indicated no significant difference between the experiment and control groups in terms of variables like job, gender, educational level, marital status, diabetes, hypertension, high cholesterol level, and smoking history [Table/Fig-2].
Demographics of the experiment and control groups
| Variable | Experiment group | Control group | Sig. |
|---|
| n | % | n | % |
|---|
| Gender | M | 31 | 62 | 30 | 60 | p=0.431 |
| F | 19 | 38 | 20 | 40 |
| Educational level | Illiterate | 1 | 2 | 0 | 5 | p=0.152 |
| Elementary | 4 | 8 | 5 | 10 |
| Junior high school | 10 | 20 | 10 | 20 |
| High school | 23 | 46 | 25 | 50 |
| College | 12 | 24 | 10 | 20 |
| Marital status | Unmarried | 5 | 10 | 7 | 14 | p=0.325 |
| Married | 45 | 90 | 43 | 86 |
| Job | Housekeeper | 13 | 26 | 12 | 24 | p=0.122 |
| Retired | 8 | 16 | 10 | 20 |
| Employee | 29 | 58 | 28 | 56 |
| History of smoking | Positive | 17 | 34 | 16 | 32 | p=0.118 |
| Negative | 33 | 66 | 34 | 68 |
The results showed no significant difference between the experiment and control groups before the intervention in terms of attitudes, subjective norms, perceived behaviour control, intention and score of lifestyle. Three months after the intervention, however, the experiment group showed a significant difference in terms of the mentioned variables comparing with the control group [Table/Fig-3].
Mean score of attitudes, subjective norms, perceived behaviour control, intention and score of lifestyle before and three months after the intervention in the control and experiment groups.
| Variable | Group | Before interventionM±SD | After interventionM±SD | p-value |
|---|
| Attitudes | Experiment | 26.3±4.22 | 57.32±4.23 | p<0.001 |
| Control | 26.22±4.36 | 27.44±4.09 | p=0.127 |
| p-value | 0.265 | p<0.001 | |
| Subjective norms | Experiment | 28.28±2.28 | 63.11±3.34 | p<0.001 |
| Control | 27.81±3.15 | 29.10±3.53 | p=0.521 |
| p-value | 0.221 | p<0.001 | |
| Perceived behaviour control | Experiment | 28.22±3.60 | 59.32±4.26 | p<0/001 |
| Control | 27.08±2.32 | 28.10±2.31 | p=0.434 |
| p-value | 0.340 | p<0.001 | |
| Intention | Experiment | 26.31±3.16 | 62.37±3.66 | p<0.001 |
| Control | 25.98±3.49 | 26.45±3.14 | p=0.566 |
| p-value | 0.276 | p<0.001 | |
| Lifestyle | Experiment | 23.43±3.36 | 57.88±3.65 | p<0.001 |
| Control | 23.78±3.61 | 24.20±3.28 | p=0.328 |
| p-value | 0.257 | p<0.001 | |
Discussion
Application of TPB to change lifestyle of patients with MI was examined. The findings showed that the constructs attitudes, subjective norms, and perceived behaviour control were predictors of intention to change lifestyle in the subjects by explaining 39.6% of intention to change behaviours. Moskhi M et al., studied the factors pertinent to lifestyle based on TPB and found that attitudes construct was a notable predictor of intention for having a healthy diet [26]. Zoellner J et al., and Yekaninejad M et al., reported that the constructs of TPB predicted a high percentage of intention [27,28]. Blandchard CM et al., studied 215 heart patients and found that the construct of TPB predicted 30% of variance of intention to do exercise [29]. In the study of Ferreira G et al., TPB predicted 45% of behavioural intention [30].
The results of the interventional study indicated effectiveness of the interventions based on TPB on improving lifestyle of the subjects, hence there was a significant difference between the control and experiment groups after the intervention in terms of healthy lifestyle. Borji M et al., reported a significant increase in MI patients intervention group comparing with those in a control group in terms of their attitudes about risk factors of the disease after an educational intervention based on Health Belief Model [31]. Abbaszadeh A et al., showed that an educational intervention for MI patients improved their attitudes [32]. Karimy T et al., demonstrated that the educational intervention based on TPB improved attitudes of MI patients [22].
Mean score of subjective norms after the educational intervention in the experiment group increased significantly comparing with the control group. White KM et al., examined the effects of behavioural intervention based on TPB on improving physical activities and healthy diet in elderly subjects with CVDs and diabetes type II comparing with the control group, and reported an increase in the construct subjective norms of physical activity in the experiment group after the intervention. However, in terms of diet there was no notable difference between the two groups in terms of the constructs of TPB [33]. Our results are consistent with Karimy T et al., that educational intervention improved construct subjective norms of lifestyle change in the experiment group comparing with the control group [22] and Gholamnia-Shirvani Z et al., showed that educational intervention improved construct subjective norms of physical exercise behaviours in the experiment group comparing with the control group [34]. Mean score of perceived behaviour control in the experiment group increased significantly after the intervention comparing with the control group. Kelley K et al., used educational booklet about healthy life containing topics on motivation and goal setting strategy and reported an increase in mean score of perceived behaviour control after the educational intervention [35]. Our results in this regard are consistent with other studies [22,33,34,36]. Educating healthy lifestyle skills through educational courses along with providing motivational feedbacks and information through group discussions improved perceived behaviour control in the experiment group.
Results about intention of the MI patients to change their lifestyle showed a significant increase after the intervention in the experiment group comparing with the control group. Taking into account TPB, increase in mean scores of attitudes, subjective norms, and perceived behaviour in the experiment group in the three months period after the intervention led to increase of behavioural intention in the subjects; this indicates positive effect of the intervention. In this regard, the findings here are consistent with Hill C et al., interventional study, where a theory-based motivational brochure was utilized along with a motivation and intention implementation strategy test [37]. Parrott M et al., interventional study resulted in an increase in mean score of physical exercise activity at follow-up stage (two weeks after invention) and a decrease at retention stage (one week after the follow-up stage) [38]. Karimy T et al., reported that educational intervention based on TPB improved MI patients’ intention in the intervention group for changing their lifestyle [22]; they stated that there was a significant increase in the score of lifestyle in the intervention group. Karimy T et al., Krumholz HM et al., Pischke CR et al., Kurcer MA et al., and Sadeghi R et al., mentioned that educational intervention improved lifestyle of heart patients in the experiment group comparing with the control group [22,39-42]. Wu J-R et al., studied adherence of low-salt diet in heart failure patients using TPB and showed effectiveness of their intervention (based on the theory) on improvement of nutrition in the subjects in the experiment group [43]. Welsh D et al., studied effects of educational intervention based on TPB on low-salt diet in heart failure patients and showed that sodium intake of the intervention groups was less than that of the control group six months after the intervention [21]. Ali AL et al., Zigheimat F et al., Pfaeffli Dale L et al., and Broekhuizen K et al., showed that educational intervention improved performance and lifestyle of heart patients [44-47]. TPB education to promote healthy lifestyle and decrease risk of CVDs can lead to an increase in information of the subjects and changes in social norms and values about lifestyle.
Limitation
The strength of this study were community-based educational intervention based on the theory of planned behaviour on patients with MI. Socioeconomic factors and intervention in them are also important variables that were ignored in the current study and should be addressed in future studies. The main limitation of the present study was that we were not able to assess the long-term effects of the program. Other limitation of this study was self-reporting of participant’s behaviours.
Conclusion
The results supported effectiveness of educational interventions based on TPB on improvement of lifestyle of MI patients. One may conclude, then, that by using this theory it is possible to modify and change attitudes, subjective norms, perceived behaviour control, and behavioural intention of MI patients in terms of unhealthy lifestyle and improve their lifestyle eventually. Applying and examining the effectiveness of this theory about other chronic diseases in particular in which lifestyle plays a key role can be a subject of future studies.
Ethics Committee Approval: The research plan was approved by research council of Fasa University of Medical Sciences.