The Effect of Educational Intervention Based on the Theory of Planned Behavior on Nutritional Behavior with Regard to Cardiovascular Diseases Among Health Volunteers
 
Esmat Rezabeigi Davarani; MSc¹, Mohammad Reza Mahmoodi; PhD*²,
Narges Khanjani; PhD³ & Mohammad Mehdi Fadakar; PhD^4
 
1 Health Services Management Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran.
² Physiology Research Center, Institute of Basic and Clinical Physiology & Department of Nutrition, School of Health, Kerman University of Medical Sciences. Kerman, Iran.
³ Neuroscience Research Center, School of Health, Kerman University of Medical Sciences, Kerman. Iran.
⁴ Social Determinants of Health Research Center, Institute for Futures Studies in Health, School of Health, Kerman University of Medical Sciences. Kerman, Iran.
 

 
Introduction

 bulk of epidemiological evidence indicates that the dietary pattern of people has undergone a rapid change in low- and middle-income nations. This nutritional transition has led to excessive intake of energy-dense diets high in unhealthy saturated fats, tropical oils (e.g., palm oil), sodium, and sugars, which have increased the risk of cardiovascular diseases (CVDs) (Buttar et al., 2005). The main determinants for the rise of CVDs among nations at all stages of development include diabetes, dyslipidemia, hypertension, tobacco use and exposure, unhealthy dietary changes (fats, oils, salt, and increased calories), and reduced physical activity. On the other hand, the main determinants for the drop of CVDs in some countries include declines in cardiovascular risk factors and healthful dietary shifts (Della et al., 2008) . The incidence of CVDs can be reduced by approximately 80 percent after modification of people’s lifestyle, such as increase of physical activity, modification of dietary pattern, and smoking cessation. The preventive approaches against CVDs must be tailored at a primary health promotion level(Fila and Smith, 2006) .
Theory of planned behavior (TPB) is one of the most widely used health behavior change techniques from the 22 techniques used in CVD prevention and treatment (Kelly and Fuster, 2010) (Kelly and Fuster, 2010). White et al. revealed the effect of intervention on behavior change with regard to the mediating role of planning. Furthermore, TPB-based interventions, including approaches of planning may encourage physical activity and other positive health behaviors among older people with diabetes and cardiovascular diseases(Hu, 2008) . This model is capable of explaining the differences among individuals' consumption of fruit and vegetables. It also can increase fruit and vegetable consumption in societies, where consumption of this dietary group is low (Kiamco-Millman and Pinto-Zipp, 2013) .
Major changes with regard to the use of health services have recently occurred as one of the government's strategies. Majority of countries have principally developed in providing health services due to the participation of community (Kothe et al., 2011). Hence, community involvement in health affairs has started since 1990 as an experimental plan in the capital of Iran (Tehran), comprising 160 health volunteer females. The first requirement to implement and continue the plan was activating health services in large cities(Zakus, 1998) . Health volunteers were trained with appropriate and adjusted educational methods by 4000 efficient instructors all over the country. Therefore, these health volenteers could attain the ability to train the families under their own supervision to solve life and health problems of the society (Zakus, 1998) .
Consequently, the effectiveness of educational interventions was confirmed by education and empowerment of health volunteers and led to the community and households' health. Therefore, the aim of this research was to investigate the influence of educational intervention based on the TPB on nutritional behaviors in order to prevent CVDs among health volunteers in the Kerman Health Center.
Materials and Methods
Participants of Study: This quasi-experimental study was conducted on 128 active health volunteer females, who were selected by the census. Informal consent was obtained from all participants.  Later, 65 and 63 participants were randomly assigned into the intervention and control groups. Data were collected before and six weeks after the intervention using a validated researcher-made questionnaire. The inclusion criteria were: 1) willingness to participate in the study, 2)  reference to the health center for at least six months, and 3) ability to understand the educational content and participate in group discussions. The exclusion criterion was  unwillingness to continue the cooperation due to any reason. After receiving the required permissions and coordinating with the health centers, the health volunteers were educated and trained in routine classes. Prior to the intervention, participants were provided with the study purpose and were ensured about the information confidentiality.
Protocol and Educational Package of Study: At first, a pre-test was conducted to assess the knowledge and TPB constructs in the intervention and control groups. Then, a statistical analysis was carried out on the initial data. The educational content was determined based on the results and the training program was developed for the intervention group. The training sessions were held in six 90-minute sessions. The teaching method in the training sessions included lectures and group discussions with questions and answers. The training sessions were conducted by coaches who were staff members of the health center.
At the first session, the subject of CVDs and its related risk factors were lectured. Later, some questions and answers were conducted in this regard. At the second session, general information on nutrition as well as the role of nutrition in the prevention of CVDs were educated and discussed. At the third session, in order to create a positive attitude and to revise the participants' misconceptions in the field of nutrition and cooking, the educator discussed with the health volunteers. Furthermore,  exchange of thoughts and personal experiences were directed by the educator. At the fourth and fifth sessions, the external and internal factors facilitating nutritional behavior were discussed, respectively. At the sixth session, individual ability and ease or difficulty of behavior was discussed.
In order to promote learning, the educational pamphlets were distributed among the participants. To examine the influence of program on the subjective norm, health volunteers took part in classes with their husbands and other family members. Participants were also provided with the educational materials as a training guide. The data were recollected after a six-week follow-up in order to evaluate the influence of the program and to compare the intervention and control groups.
The structured questionnaire consisted of demographic variables, knowledge questions, and TPB constructs. The TPB constructs, included attitudes, subjective norm, perceived behavioral control, behavioral intention, and nutritional behavior. The three TPB constructs of the structured questionnaire were designed based on a modified 5-point Likert scale and consisted of attitude (10 questions), subjective norm (6 questions), and perceived behavioral control (8 questions). On the Likert scale, 1 = strongly disagree and 5 = strongly agree. The other two constructs consisted of behavioral intention (7 questions) and nutritional behavior (10 questions) and were based on a modified 5-point Likert scale. On the Likert scale of behavioral intention 1 = very low probability and 5 = very high probability. On the Likert scale of nutritional behavioral 1 = never and 5 = always. To measure the participants’ knowledge, the participants should answer to a 14-item questionnaire. Each item had three options “right”, “wrong”, and “I do not know”. Each correct answer received one score and wrong answers or I do not know option got zero.
The study was supported by Vice chancellor for Research of Kerman University of Medical Sciences (Grant No: 93.441) and the protocol was approved by the review panels and ethics committees of Kerman University of Medical Sciences.
Content Validity: The validity of the questionnaire was determined by face and content validities. A panel of experts consisting of five content experts reviewed the questionnaire. The experts included the professionals who worked in the relted field. To calculate the content validity index (CVI), experts were asked to rate the relevance of each item, usually on a 4-point scale. The CVI was calculated for each item and for the overall scale. The content validity index was computed as 0.88 for the overall scale. This value can be considered as an evidence for good content validity.
Reliability: To determine the internal consistency of the questionnaire, 25 health volunteers completed a test-retest questionnaire. Two-week test-retest consistency of the questionnaire was measured by Cronbach’s alpha. The inter-class correlation coefficient was used to estimate the internal credit analysis among the options of the questionnaire items before and after the test. The correlation coefficients of knowledge, attitude, subjective norm, perceived behavioral control, behavioral intention, and nutritional behaviors were 0.89, 0.86, 0.72, 0.86, 0.87, and 0.75, respectively.  
Data analysis: Data were analyzed with SPSS version 21. Data were analyzed by Chi-square tests, t-test, Mann-Whitney U, and Wilcoxon tests. In this study, P-value < 0.05 was considered statistically significant.
Results
The mean ± standard deviation (SD) age of the participants in the intervention and the control groups were 40.96 ± 10.4 and 37.33 ± 9.53 yearr, respectively (P = 0.04). The mean ± SD body mass index of participants in the intervention and the control groups were 27.01±5.31 and 25.73±3.88 Kg/m², respectively (P = 0.11).
Table 1 shows correlation of the TPB constructs of participants before the intervention. As Table 2 represents, six weeks after accomplishing the educational intervention program, percentiles of the participants in the intervention group were compared with those of the control group with regard to knowledge and other TPB constructs. The results showed a good increase in the prevention of cardiovascular diseases among the intervention group. However, no increase was found in the percentiles of the control group participants with regard to the TPB constructs. Percentiles of the participants in the intervention and the control groups were 50.8 and 41.3 percent, respectively.
No significant difference was observed between the intervention and control groups with regard to the scores of knowledge, attitude, subjective norms, perceived behavior control, behavioral intention, and nutritional behavior before the intervention. However, the intervention and control groups were significantly different in their scores of knowledge, attitude, behavioral intention, and nutritional behavior (P < 0.0001, P  = 0.016, P  = 0.006, P  = 0.027, respectively) six weeks after the intervention (Table 3).
Table 3 also indicates the mean differences of the two groups before and six weeks after the intervention. A significant difference was alo observed in the intervention group with regard to the scores of knowledge, attitude, subjective norms, perceived behavioral control, and nutritional behavior (P < 0.0001, P  = 0.0001, P  = 0.018, P  = 0.007, and P  = 0.0001 respectively) six weeks after the educational program. No significant difference was seen in scores of the TPB constructs in control group after the educational program.
Table 4 shows the mean differences in the scores of nutritional behaviors of participants, which influenced nutritional performances of the intervention and control groups at baseline and six weeks after the intervention. Significant differences were also observed in the intervention group participants' nutritional performance considering their nutritional behavior changes during the intervention.