Introduction
Noncommunicable diseases are among the major causes of death in the world [1]. Today, hypertension (HTN), as one of the most important risk factors for cardiovascular disease, has become a growing health problem that affects people from different ethnicities [2]. Risk factors and predictors of high blood pressure (BP) include overweight, improper nutrition, alcohol consumption, low physical activity and psychological, social, environmental and genetic factors. HTN is a major risk factor for kidney disease, stroke, peripheral vascular disease and congestive heart failure [3]. The prevalence of HTN ranges from 15% to 37% worldwide. India and China have the highest prevalence rate of HTN [4]. In 2015, 13% of all global mortality (7.1 million), 62% of all strokes, and 49% of all myocardial infarctions were attributed to HTN [5].
HTN is a major modifiable risk factor for noncommunicable diseases. Effective treatment for HTN substantially reduces the risk of developing cardiovascular complications [6]. However, despite these benefits, the overall rate of HTN is alarmingly high worldwide, and this condition has caused a high burden of HTN‐related diseases [7]. HTN, although easily diagnosed and common, is often asymptomatic and can lead to death and disability if left unchecked [8]. 
There are several strategies for controlling HTN, including lifestyle modifications, drug therapy, or combined interventions. Therefore, empowering hypertensive patients by education may be an effective step in controlling HTN or reducing its complications [9]. One of the effective strategies for controlling high BP is educational interventions [10]. Many educational interventions are effective in controlling HTN. The common interventions for preventing HTN include behavioral modifications and lifestyle changes such as promoting a healthy diet, physical activity and avoiding stress and mental pressure [11]. The correct use of health education, health promotion models, and theories in teaching the public can effectively control HTN [12]. Correct education and regular educational programs can improve people’s knowledge and skills and improve their ability to make correct health decisions [13]. Research shows that the most effective educational programs are based on theory-based approaches rooted in behavior change models; therefore, choosing the appropriate health education model is the first step in the planning process of an educational program [14].
Since a major part of HTN control is the responsibility of individuals, informing patients on how to control HTN seems necessary. However, the value of any educational intervention depends on its efficiency in changing health behaviors. Educational effectiveness can be enhanced by using behavioral theories or models [15]. People’s knowledge and perceptions play an important role in controlling HTN. This systematic review summarizes the effectiveness of educational interventions in controlling high BP.

Methods

Search strategies
The study search was done between January 15, 2023, and June 20, 2023. Eight databases, including Scopus, Google Scholar, PubMed, Medline, Embase, Web of Science, SID, IranMedex and Magiran, were searched for English or Persian studies about educational interventions to control BP. The keywords used for the search are shown in Table 1. The only filter used while searching was the type of article, as we were looking for interventional studies.



Also, some gray literature, including trial registry resources and conference proceedings, was searched. In addition, we checked the bibliography of the relevant retrieved articles to find more eligible papers.

Inclusion and exclusion criteria
Inclusion criteria included an original educational intervention to control BP in inpatients aged >18 years.
Exclusion criteria included studies with the outcome of HTN and other noncommunicable disease control together, studies that tested interventions that were only adherence to BP medication, studies that included interventions that had been done for other diseases besides BP, review studies, protocols, and ongoing trials, and non-interventional studies.

Quality assessment
The preferred reporting items for systematic reviews and meta-analyses (PRISMA) was used to report standard studies. It is an evidence-based minimum set for reporting in systematic reviews and meta-analyses. The checklist contains 27 items on the content of a systematic review and meta-analysis [16]. Also, the Cochrane risk of bias (ROB) was used to determine the quality of selected studies. The biases evaluated can be seen in Table 2. Judgment of each item was either “unclear,” “high,” or “low” ROB [17].




All studies meeting inclusion criteria for the review were assessed independently by two of the authors (Reza Sadeghi and Victoria Momenabadi) for random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data (attrition bias), selective reporting, and other biases of concern. Studies at high ROB in one or more domains were classified as overall high risk, while those with unclear information in any domain were classed as moderate risk. Low-risk studies met low-risk criteria for each domain [18].

Extracting data
Two authors (Reza Sadeghi and Mohammad Reza Zeid Abadinejad) assessed the quality of the studies, screened all abstracts and if necessary, independently screened the full-text articles. Disagreements were resolved by discussion and if no agreement was reached, a third independent person acted as an arbiter. All articles were checked according to the inclusion/exclusion criteria. How to deal with missing or incomplete data was handled by consensus and additional information about the study design was requested from the corresponding author if necessary.
The information extracted was in a standard form. It included the location of the study, the year the study was conducted, the type of study, the population size and target group, characteristics of the intervention, and study results (Table 3). 






Results 
After searching the electronic databases, a total of 4467 related articles were retrieved, of which 1812 were Farsi and 2655 were English. Of these articles, 2625 articles were deleted due to duplication. Further, out of 1842 articles, 1821 were excluded from the study due to being a review, not having a consolidated standards of reporting trials (CONSORT) score, being a protocol, an ongoing trial, a non-interventional study, or being about controlling HTN and other conditions altogether. Five studies were excluded due to low quality. The quality assessment results are shown in Table 2. Finally, 21 studies entered the review (11 Persian and 10 English articles) (Figure 1).



The characteristics of 21 articles can be seen in Table 2. A positive effect of education on controlling HTN was shown in all educational interventions. Still, studies aimed at self-care education [19, 20] seemed more effective, because the difference between the intervention and the control group was higher (Table 3).
The follow-up time for the study participants was between 1 and 6 months. Different educational methods such as lectures, questions and answers (Q&A), group discussions [23, 24], face-to-face training sessions [19], counseling [25], telephone consultation [1] and PowerPoint presentation [34] were used as the intervention. Some studies used interventions that reinforced education, such as pamphlets, brochures, training packages, and text messages [19, 21, 22, 32, 36].
In some studies, no comparison (control) group was used [22, 26, 34, 19]; in some studies without a control group, no special intervention was done [20, 21, 23, 24, 27, 28, 32]. In all studies, the results of the pre- and post-intervention in the control group were not significantly different.
The aim of some studies were educating about lifestyle modification, such as decreasing excessive salt, and saturated [19] or trans fat consumption [36], increasing fruits and vegetables intake [19, 35, 36], decreasing stress [35, 36, 38], increasing physical activity [20, 23, 27, 36, 38], and reduced consumption of tobacco and alcohol [35, 36]. In Mattila’s study, a multidisciplinary lifestyle intervention was conducted in a rehabilitation center [32].
In the included studies, various individual or community-based interventions, including family-centered [25], person-centered [19], texting [31, 37, 38], training in group sessions [20, 22, 24], multiple interventions [23, 24] and community-based interventions [38] were applied. Victor et al. used barbershops as educational sites for African American men [44]. Two studies aimed to improve self-care or the self-management of HTN [19, 20].
The educational models used in the included studies were KAP (knowledge, attitude and practice) [26-28], the PRECEDE-PROCEED model [27], the health belief model [2], the BASNEF model [20, 31] and the theory of planned behavior [31]. 

Discussion 
This systematic review included 21 studies on educational interventions to control HTN, with various individual or community-based interventions. These studies provided relevant information about the effectiveness of the different health education interventions.
Researchers have used various educational models for behavior change. Well-designed health education theories/models can help change behavior and improve health outcomes [31, 45]. The value of an education is determined by its effectiveness in modifying or creating positive health behaviors [46]. However, behavioral science models/theories should be used appropriately to show their maximum impact [44]. The readability and suitability of educational material and choosing the right communication route are the most important and neglected points in increasing the quality and quantity of education [47].
Some studies included in this review aimed to improve self-care or the self-management of HTN. Self-care provides disease prevention, maintains health, and complies with treatments, by the individual [48]. One of the goals of empowering people through education and increasing health literacy is promoting self-care [49]. Therefore, educational interventions should be designed to help people understand the aspects of their disease and perform appropriate self-care. Bosworth’s study showed that HTN self-care monitoring at home and tailored behavioral telephone interventions improved BP after 24 months [1]. Some researchers think a decrease in BP may encourage the patient to modify their lifestyle or continue treatment [9].
The aim of some studies included in this review was lifestyle modification. This objective included changing diet, decreasing stress, increasing physical activity, and consuming tobacco and alcohol. Lifestyle modifications can help normal and hypertensive patients prevent or reduce high BP [50]. The study results of Putri et al. showed that lifestyle factors affecting the incidence of HTN in adolescents are smoking, body mass index, physical inactivity, sleep duration, alcohol use and inappropriate diet [51]. Also, Ribeiro et al. study showed lifestyle modification is widely recommended as the first-line treatment for the management of HTN and includes smoking cessation, modifying the diet, increased physical activity and reduced alcohol consumption [52].
Controlling high BP is a challenge in public health. But HTN is a modifiable risk factor [19] and many educational interventions are effective in preventing and controlling HTN. The difference in effectiveness of the interventions may be due to the different nature of the interventions, complementary education material, follow-up time, individual or community-based, and the specific educational models used.
One of the limitations of this review was that it only searched Persian and English databases. Another limitation was that the included studies had a short follow-up time after the interventions, from 1 to 6 months. It is suggested that future studies conduct longer follow-ups to evaluate the long-term effects of these interventions. Another limitation of this study was that the studies were diverse regarding the model, theory, and method of education and the outcome measured; therefore, a meta-analysis was impossible.

Conclusion 
Many educational interventions and training methods are effective in the control of HTN. Educational interventions are a cheap and applicable way to promote self-care behaviors in patients with high BP.

Ethical Considerations

Compliance with ethical guidelines
All information sources used in this study had been published before and were therefore in the public domain, but general ethical principles were applied. The researchers maintained integrity, objectivity, thoroughness in searching and adherence to the highest possible technical standards.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
Conceptualization and study design: Reza Sadeghi, Victoria Momenabadi, Mohammad Reza Zeid Abadinejad and Narges Khanjani; Data collection, data analysis, data interpretation and drafting the manuscript: Reza Sadeghi and Narges Khanjani; Review and editing: Mahmoud Reza Masoodi, Narges Khanjani, and Reza Sadeghi.

Conflict of interest
The authors declared no conflict of interest.




References