Can Nutrition Education Improve the Nutrition Behavior and Anthropometric Indexes among Patients with Hypertension based on the Health Promotion Model?

Background: Following the rapid urbanization, unhealthy diet, enhanced life expectancy, and sedentary lifestyle has led to an increase in the prevalence of CVD and its risk factors, such as hypertension. Self-care is introduced as “behaviors directed toward oneself or the environment to formulate one’s functioning in the interest of one’s life, and well-being. Can nutrition education improve the nutrition behavior and anthropometric indexes among patients with hypertension based on the Health Promotion Model? Methods: A quasi-experimental and single-blind study was conducted on patients with hypertension attended to the Health Houses of Gorgan city of Iran between June 2018 and February 2019. To collect information, 68 patients in the control and 68 ones in the intervention arm were investigated. Data were collected by distributing self-administered questionnaires about HPM constructs, and testing 3-day diet record. Education was just conducted in the intervention arm including six sessions during three weeks, and in nal, measurement was run two and six months after intervention. Results: There was no difference between the two groups about constructs of the HPM, anthropometric indexes, systolic and diastolic blood pressure and nutritional behavior before education, while after education all variables were signicantly changed in two and six months’ follow-ups. Conclusion: HPM-based education might be likely useful to improve nutritional behaviors in patients with hypertension and it can also be applied in the health system of Golestan Province. plans of action Numerous studies well documented that HPM model could be benecial as a theoretical framework to nd major determinants of adherence to the chronic conditions such as hypertension (20), prediction of self-care adherence in patients undergoing coronary angioplasty (21), and prediction of nutritional behavior among diabetic patients (22). effectiveness of education anthropometric indexes and dietary commitment among patients hypertension


Introduction
Cardiovascular disease (CVD) results in 17 million deaths per annum, nearly one-third of all deaths in global (1). Hypertension is a largely preventable risk factor for death and disability for CVD worldwide that can be controlled and treated (2,3). The prevalence of hypertension is globally projected to augment from 26% in 2000 to 29.2% by 2025 (1) Annual premature death of 7.7 million and 6% of burden of disease (GBD) is universally attributable to hypertension (4). Given the numerous studies conducted in Iran, the prevalence of hypertension reported 25-35 % in general (5), which is reported as the rst cause of mortality in Iran (6). It is widely associated with chronic complications, including CVD and strokes (7).
Following the rapid urbanization, unhealthy diet, enhanced life expectancy, and sedentary lifestyle has led to an increase in the prevalence of CVD and its risk factors, such as hypertension (8).
Body Mass Index (BMI) has widely documented to be one the most leading risk factor of several speci c causes, including CVD (9). In global, prevalence of obesity and obesity-associated diseases, particularly hypertension, have been increasing. The mean of BMI increased by 0.4-0.5 kg/m2 per decade in men and women during 1980 and 2008 years across the world (10). According to the several studies, a high BMI is known as an independent risk factor for morbidity and mortality from CVD and some cancers in the population (11). Obesity is also a leading risk factor for many chronic diseases and can result in metabolic, orthopedic and cardiovascular diseases, as well as cancer (12).
Self-care is introduced as "behaviors directed toward oneself or the environment to formulate one's functioning in the interest of one's life, and well-being (13).
Opinions and judgments of people play key roles to implement self-care behaviors (14). It is well documented that opinions and believe are essential in an emergence of behavior and also unhealthy behaviors considered as the major cause of hypertension. Perceptions are among the main predictors of behavior The current study was conducted in Gorgan city of Iran between June 2018 and February 2019. The study protocol was approved by the Ethics Committee of Golestan University of Medical Sciences. Patients suitable for inclusion were as follows; a de nitive diagnosis by a physician, having a health record in the Health House, lack of chronic and severe complications, no other lasting diseases, aged between 30 to 65 years, no history of surgery or hospitalization in the last three months, willingness to participate in the study, lack of speci c mental illnesses and no dementia, and those excluded if they did not meet the following criteria; pregnancy during the study, need a special diet, involved with diseases and absent more than two sessions in the educational interventions. Prior to the study, the informed written consent was obtained by all patients.

Outcomes
The primary outcomes were nutritional behavior that measured by the HPM-based standard questionnaire and 3-day diet record. While, the secondary ones were anthropometric indexes that tested using waist circumference, body weight, height, and BMI variables as well as hypertension.

Interventions
The present study was run in four stages, including, 1) educational planning, 2) sampling, 3) intervention and 4) evaluation.

Educational planning
A cross-sectional study was conducted to determine the effect of Pender Health Promotion Model constructs in predicting nutritional behaviors in patients with hypertension. By exploring the data, path analysis identi ed the most important factors affecting nutritional behavior. In nal, education content was provided according to the cross-sectional study and Dietary Approach to Stop Hypertension (DASH).

Sampling
Four Health Houses were recruited. Before intervention, data were collected by distributing questionnaires about model constructs, 3-day diet record and their anthropometric indices.

Educational intervention
Education was just conducted in the intervention arm, including six sessions during three weeks (two sessions per week, 30 to 45 minutes for each session, and 17 patients were participated in each session). A brief overview of hypertension, symptoms, and side effects of non-controlling illness was presented by a public health student at the Health House for 10 minutes. At the end of the training sessions, nutrition education pamphlets were distributed to all study participants. Participant in the control group was only received the routine education for patients who usually provided by the health care personnel working in the Health Houses.

Evaluation
All participants had two and six months' assessments by personnel who were not involved in supporting the interventions.

Measurements
To measure BP, the patients were not recently indulged in any activity similar exercise or eating that may likely affect the BP, also the patients were quietly rested in a comfortable chair for 3 to 5 minutes with the upper arm at heart levels were tested. Three measurements were done in succession, separated by at least one minute (25).
Waist circumference was measured in the mid-axillary line at the midpoint between the costal margin and the iliac crest. Body weight was assessed to the closest 100 g. Height was estimated with a stadio-meter to the nearest one mm, and then BMI was calculated as weight (kg)/height(m2)(26).
Nutritional behavior was measured using 3-day diet record (two normal days and one day off) and were also coded and veri ed by registered dietitians. In brief, it was estimated based on the energies consumed by macro and micro-nutrients.
All measurements were performed at pre-intervention (baseline), two and six month follow-ups.

Sample size
The sample size was estimated based on the repeated measurements as follows; correction factor (R= 0.44) in accordance with 0.6 of pre-test observation number (v=1) and pre-test observation number (w=2), signi cance level of 0.05, statistical power 80 % and the standardized effect size of 0.2, 124 patients were estimated that with consideration of attrition risk, 136 patients (68 patients in the control arm and 68 patients in the intervention arm) were recruited.

Implementation
Cluster sampling method was used such that from 80 Health Houses in the Golestan Province, 10 percent of them selected based on the systematic random sampling. Four Health Houses for the control arm and four ones for the intervention arm were enrolled. In total, 17 patients were provided with education in each Health House (68 in the control and 68 in the intervention arm).

Blinding
A single-blind study was implemented such that participants were blinded after assignment to the intervention.

Data analyses
T-test was used for comparing the means of two independent groups. One-way ANOVA was performed to examine means before and after intervention. For two dependent groups paired t-test was used. Repeated Measures ANOVA was examined in independent groups to nd differences between groups over time.
To predict the patient's nutritional behavior based on the HPM model, Linear Regression model was also used. Data analyzed by the SPSS software for windows (version 18), moreover, nutritionist (N4) software (version 4) was used to test nutritional variables. A P-value of <0.05 was considered signi cant. There was no difference between the two groups about constructs of the HPM before education (baseline); while after providing education, all scores of the constructs were signi cantly increased in two and six months' follow-up (p <0.001) (table 2). Table 2 The mean and comparison of the HPM constructs between the intervention and control groups at the baseline, 2 and 6 month follow-up Given table 3, all anthropometric indicators, including waist, weight and BMI were remarkably decreased 2 and 6 months after the education in the intervention group (p <0.001). Moreover, a statistical signi cant difference was found between the two groups in terms of SBP and DBP 2 and 6 months after intervention (p <0.001). Macro-nutrients usage and their energy intakes were signi cantly different between the two groups in two and six months' follow-up (p <0.001), such that fat consumption was decreased, while carbohydrates and protein consumption were increased in the intervention group at two and six months' follow-up (table   4).  Table 5 indicates that all the constructs of the HPM predicted the patient's nutritional behavior when they were entered in the model separately. While, after adjustment, four of them, namely perceived bene ts (P=0.001), nutritional knowledge (P=0.001), perceived self-e cacy (P=0.023), and affects related to the behavior (P=0.001), were able to signi cantly predict the patient's nutritional behavior. ANOVA repeated measure illustrated that score of the constructs, anthropometric indexes, SBP and DBP as well as macro and micro-nutrients intakes were signi cantly changed two and six months after intervention (P = 0.001) (all tables).

Knowledge
Knowledge plays a key role in commitment to dietary among patients with hypertension (27) such that numerous studies mentioned lack of knowledge as a problem to control hypertension (28,29). In a study conducted by Spencer et al, poor dietary knowledge introduced as a barrier for controlling diet in DASH approach (30). At present, patients were moderately provided by the knowledge that was in associated with other studies (30,31). In relevance to present, several studies implemented in the rural area reported poor knowledge toward dietary (32,33), also investigations in the urban area indicated the same results (34,35).

Bene ts and barriers
Patients range moderate to high in the bene ts and barrier ' s scores, currently. Two aforementioned constructs describe the action of individuals by balancing or unbalancing the perceived positive and negative forces on health behavior (18). Perceived barriers in Kamran et al study were di culties in preparing lowsalt foods, deprivation of tastes of some foods, being tired of having a diet, and being deprived of party and high cost of diet foods (23).

Self-e cacy
Bandura views self-e cacy as the strongest predictor of behavior change in the individual, and those with the most behavior change usually have a higher level of self-e cacy for speci c behaviors (36). Presently, self-e cacy scores of patients were in a poor range, nearly. Our ndings were not similar to Pariad et al study that investigated the patients with cardiovascular disease (37). In addition, Waren et al found good self-e cacy for patients with hypertension, although they studied self-e cacy for weight loss (38). The majority of our patients were female villagers with low literacy that might be the reason of their low self-e cacy, since factors such as age, gender, education level and area of residence as well as access to health services can affect self-e cacy (37).

Interpersonal in uences
Social in uence and the effects of others, including family members have been identi ed as both a facilitator and a deterrent to blood pressure control (39). Family members play a vital role in the self-care, including help to select and preparation of food (40), assisting in the perception and adherence to nutritional recommendations (39), facilitating communication between the patient and care providers and talking about hypertensive care (41) and encouraging behavior change (39). Presently, the score of the construct was improved that might be likely due to family support, especially a spouse for adhering to the diet.

Situational in uences
This construct importantly affects on diet commitment. Horowits et al found that it is impossible to follow the nutritional recommendations provided in the community in which they live, because their environmental and cultural conditions were unsuitable for their application (42). In a study done by Guardia et al, environmental conditions had a signi cant effect on behavioral intention to reduce sodium in meat products and acceptance of low sodium sausages (43). In brief, nutritional behavior is in uenced by individual, psychological, and social factors that are important for understanding and establishing the necessary contexts for behavior change.
4.6 Affects related to behavior

SBP and DBP
Hypertension is a result of genetics and environmental factors that nutrition is the most important one. Nutritional intervention can be considered as the rst step before initiating drug therapy and in people taking the medication adherence can help to decrease BP (56). Currently, SBP and DBP were remarkably decreased in the intervention group at all follow-ups. A number of studies have indicated a positive effect of the DASH approach to decrease hypertension (57,58). Of course, the DASH approach has not always been bene cial (59,60). At present, the success of DASH approach can be likely due to the theoretical framework used in this intervention, commitment to behavior, training to improve behavioral perceptions and optimal dietary follow-up.

Anthropometric indexes
The current results reported signi cant differences during follow-ups in the intervention group that also indicated by other scholars such that DASH approach could decrease the obesity (61). In a controversial result, Aucott et al found that although weight loss was maintained, but SBP increased and returned to the pre-intervention stage. In the aforementioned review study, BMI and waist were signi cantly decreased two and six months after intervention (62). Positive effect of weight loss on blood pressure control is recommended (38). Extensive communication, rational goals, continuous monitoring is effective weight loss strategies. Furthermore, nutrition and lifestyle changes are the forefront of a weight loss strategy (63).

Macro and micro-nutrients
As the DASH approach expects, at present, fat and protein consumption was decreased while carbohydrate usage was increased. In association with our study, other ones delineated that DASH approach-based interventions resulted in decrease in fat consumption (52,64). The DASH approach emphasizes the consumption of high-carbohydrate diets (complex carbohydrates) including grains, vegetables and dietary ber (65). In some studies investigating the relationship between carbohydrate intake and blood pressure, con icting results have been found including, direct association and inverse association (66) and in others not signi cant (56). Protein intake was also decreased in the intervention group that was in accordance with other studies (67,68). Although, incompatible results were found, as well (69). The type of protein consumed (animal, plant) may have different effects on blood pressure (69). According to the DASH approach, reduce sodium intake and increased intake of potassium, calcium and magnesium can decrease hypertension (70). It is recommended to limit salt intake in patients with hypertension and abnormal blood pressure of 5 to 6 grams per day, which may be effective in lowering blood pressure (71) that partly achieved in the current intervention group. DASH approach, especially emphasizes on consumption of low-fat dairy products that achieved in the intervention group. Potassium intake in most countries is below the recommended level (72). The recommended potassium level in the DASH approach is 4700 mg (73), which despite the signi cant increase, did not reach the recommended target for the intervention group.

Conclusions
Hypertension is widely increasing among the Iranian population in the rural and urban area due to civilization and sedentary lifestyle. According to the Golestan health system statistics, hypertension has always been a major public health problem that imposes a huge burden on the health system despite all health care services. Therefore, the current ndings might likely be bene cial as a theoretical education framework by replacing the new educations by the old and affect less ones.

Strength And Limitation Of The Study
The present study as a framework-based study implemented to identify factors of hypertension that rarely done among housewife Iranian society. Also, to better nd the effectiveness of intervention, 2 and 6-month follow-ups were measured. However, the study was conducted only among women which limits its generalizability.

Funding
The study protocol was nancially supported by the Golestan University of Medical Sciences.