To the best of our knowledge, this is the first clinical trial to evaluate the effectiveness of CBT on dietary adherence in patients with IHD. This study was performed on 50 IHD patients, including 17 females (34%) and 33 males (66%). The high frequency of male sex is consistent with the report published by American Heart Association [14]. In addition, most studies have also described male sex as a risk factor for the onset of the disease [15]. For example, in a study conducted by Youn et al. [16], the male/female ratio of CVD incidence was reported to be 5 to 3. Although recent studies suggest a decrease in the incidence of this disease in men and an increase in women [15], the male gender is still considered as a major risk factor for the onset of this disease. In the present study, the mean age of the patients participating in the study was 61 years, and the high age of these patients was similar to other studies [15, 17]. The CBT is a combination of cognitive and behavioral approaches in which the patient must be able to identify and modify distorted thinking patterns and ineffective behaviors. Since this approach can be influenced by several factors such as educational level, occupation [11], the random sampling was done by minimization method in order to homogenize the two groups in terms of demographic variables (Tables 1 and 2).
Dobson et al. pointed out that cognitive-behavioral outcomes are useful for patients with concurrent disorders, since knowing the factors affecting the disease and reducing its severity and symptoms can help to improve the patient's disorder[11]. In addition, this view can be helpful for people who have no beliefs about their dietary regimen [11, 18]. The first step of cognitive-behavioral intervention is related to detect the causes of non-adherence, and the patient's barriers and difficulties in dietary adherence are examined through face-to-face interviews. These actions can be effective in identifying and removing barriers to non-adherence [11]. The results of a review study by Matteson, which aimed to investigate interventions to improve dietary adherence in patients with chronic disorders, showed that the CBT was more effective than other interventions to adhere the regimen [19].
The results of this study revealed that the CBT could affect the dietary adherence of IHD patients. In this study, the two groups were homogeneous at the baseline in terms of dietary adherence (P> 0.05). The CBT was performed on the case group for three months. In evaluating patients after 1 and 3 months, it was found that the CBT could be effective in improving dietary compliance in the IHD patients (Table 3).
In addition, in our study, the effect of time (changes in diet score during continuous measurements), the effect of the group (changes in diet score between the groups studied), and the interaction between time and group (changes in diet score over time and with taking into account the effect of the groups) showed that there was a significant difference in the intervention group at three different times (P <0.00001), but there was no significant difference in the control group, which confirms the positive effect of cognitive-behavioral intervention in Improve dietary compliance in the intervention group(Table 4)(figure 1).
Increasing the dietary adherence score in the present study can be due to the multifaceted nature of the CBT, because cognitive-behavioral therapies help the patient to become familiar with and correct their own problems, and thus these changes improve emotions and behavior of the individual [11]. The results of our study indicated the importance and influence of self-care programs in patients, which is well documented in other studies. For example, Ezzati et al. examined the dietary adherence in CVD patients and found that most CVD patients, in terms of dietary adherence, were in moderate level (60%) and a small percentage of patients had proper performance [20]. This finding demonstrates the central role of the treatment team in meeting the nutritional training needs of CVD patients and the need for self-care strategies to control diet [11].
In this study, the patients were treated with CBT for three months. The difference between the first month and the third month was significant, so that the dietary adherence score in the case group was 2809 at the end of the first month and 3504 at the end of the third month. Although this difference was significant at the end of the first month and also the third month, the long-term follow-up of this treatment seems to bring better clinical outcomes. Gary et al. examined the combined effect of CBT and exercise on patients suffering from heart failure with duration of three months. Clinical outcomes were also remarkable [21]. Some studies have also considered a shorter time to examine the impact of CBT. For example, in a study by Margo Liber et al., the patients were treated with CBT for 10 weeks and one session per week, and evaluated at the end [22]. Vázquez-Rivera et al. also showed that treatment with CBT had a positive effect on patients even in the short term (5-6 weeks). This finding is in line with our results, as the dietary adherence score was significantly increased in the case group after one month from the start of the study [23].
Our research results confirm this, so that it is necessary to establish initially an effective treatment relationship with the patients in order to improve dietary adherence, identify the causes and barriers of their non-adherence and increase their motivation to change the behavior. The results of the Baumann's study entitled "Helping patients with chronic conditions overcome barriers to self-care" showed that the first step in helping patients to self-care (including dietary adherence) is to identify their problem and to examine the reasons for non- -adherence [24]. Some strategies to overcome self-care barriers include motivational interviewing, recognizing individual beliefs, increasing self-efficacy and increasing social support [11]. In the present study, after evaluating patients and identifying the causes of dietary non-adherence, the self-confidence of patients was improved using emphatically positive statements, their motivation was enhanced to modify the behavior, and their wrong behavior in this field was corrected by creating interest and speaking problems and barriers related to dietary non-adherence.
It seems that in order to increase the patient's confidence in pursuing a healthy diet and to improve nutritional modifications in the long term, there is a need for their understanding of the specific dimensions of the disease. Therefore, the patients who believe that the dietary adherence reduces the risk of heart attack and pain, improves their cardiac conditions and prevents readmission, have a higher level of confidence in managing changes in the nutritional regimen after the onset of a cardiac event.
As we observed, the prevalence of low- educational level individuals in the control group was greater than in the case group. Recent studies have shown that if the CVD patients believe that their cardiovascular conditions might be due to poor lifestyle habits, whose modification provides the possibility of cardiovascular improvement or delay and a decrease in the frequency of hospitalization, they would be more likely to strive to make a lasting modification in their nutritional behavior [24-26]. Although this difference was not significant, it could indicate a greater understanding of the intervention group regarding their dietary adherence. In this regard, Khera et al. underlined that a modification in life style could well suppress the individual's genetic predisposition to disease[27]. Therefore, understanding the disease is a predictor of self-efficacy in dietary adherence in CVD patients to achieve desired lifestyle [27, 28]. Therefore, in order to maintain proper dietary adherence, the patient needs to have a good understanding of the disease and believes that a proper nutritional diet can prevent the progression of the disease. This suggests that understanding the disease, as a predictor of nutritional behavior self-efficacy should be emphasized in the conclusion. Considering the results of the study showed that understanding of the disease affects the nutritional behavior self-efficacy, realizing the concept of illness by patients helps health providers to organize their activities to improve their health and promote self-efficacy in CVD patients [29, 30]. Also, the results of this study, which indicate the specificity of understanding the disease in predicting the nutritional behavior of self-efficacy in CVD patients, can attract the attention of clinical nurses who play a major role in the care of CVD patients towards this point that an understanding of the disease in these patients and attempting to promote it can lead to more favorable outcomes in care.
It is important to understand the perception and knowledge of patients about the CVD conditions and to select appropriate and effective methods to improve their perception of their illness. In the field of nursing clinical education, a clinical education program can be presented so that they can plan and strive to improve the self-efficacy of cardiac patients by providing the necessary training. The nurses through implementing the CBT on cardiac patients can elevate their self-efficacy [11]. It should be noted that improving self-efficacy of cardiac patients increases their self-care ability and will prevent repeat referrals, readmission, and occupancy of beds in health centers, thereby decreasing the load of nursing activities and the frequency of repeated training courses for the dietary adherence. Given the priority of prevention over treatment, if the planning of educational managers is adjusted in such a way as to improve the self-efficacy of patients in long-term and after discharge, the final and positive feedback will be returned to the community and the nurses themselves.
Limitations
Given that the results of this study are self-reported through a questionnaire and considering the probability of individual mental conditions at the time of completing the questionnaire, it is recommended to use laboratory results to investigate the outcomes of the intervention.