Impact of Nutrition Education on Various Health-Related Components of Hemodialysis Patients: A Systematic Review

This study aimed to identify the impact of nutrition education on various health-related components of hemodialysis patients. A systematic review was conducted according to the PRISMA guidelines. Relevant literature published between 2013 and 2023 was identified across two databases (PubMed and Science Direct). The protocol was registered in PROSPERO (CRD42023460681). Two independent reviewers retrieved the data, and 41 studies were selected. Nine components related to the impact of nutrition education in hemodialysis patients were identified. Each component was clarified by mentioning each study and its results. This study enabled us to characterize the various components of the impact of nutritional education in hemodialysis patients, namely biological markers, quality of life, cost of care, adherence to dietary recommendations, knowledge, malnutrition inflammation, dietary intake, weight change, and behavior change. This systematic review enables healthcare providers to assess the impact of nutritional education on hemodialysis patients. Also, it gives professionals an exact idea of the impact of nutrition education on hemodialysis patients, with knowledge of new methods using behavior change theories and innovative technological tools.


Introduction
Statistics have revealed an increase in non-communicable diseases responsible for an estimated 41 million people dying annually, constituting 74% of all deaths worldwide [1].In the 21st century, chronic kidney disease (CKD) has emerged as a leading cause of death and disability.As risk factors like obesity and diabetes mellitus have increased, CKD patients have also increased in number.By 2017, 843.6 million people were estimated to be affected globally.Thus, increased efforts should be made to improve the prevention and treatment of chronic kidney disease due to the large number of affected individuals and the serious consequences of the condition [2].
According to the USRDS annual data report, the average annual change in the incidence of ESRD treated by country or region demonstrates an increase in most countries participating in the survey.Hemodialysis emerges as the primary treatment modality for end-stage renal failure worldwide [3].
Hemodialysis patients encounter numerous challenges, encompassing the management of fluid and phosphate intake [4], anemia, cardiovascular problems, protein-calorie malnutrition, infections, renal osteodystrophy, and interdialytic complications [5].In this regard, several alternatives are used to manage chronic renal failure, especially among hemodialysis patients, including health education.This concept is defined by the World Health Organization (WHO) as "health education compris[ing] consciously constructed opportunities for learning involving some form of communication designed to improve health literacy, including improving knowledge and developing life skills which are conducive to individual and community health" [6].In this respect, the United States National Commission for Health Education Credentialing (NCHEC) has determined the health educator's seven main duties as: "assessing individual and community needs for health education, planning effective health-education programs, implementing health-education programs, evaluating the effectiveness of health-education programs, communicating health and health-education needs, concerns and resources, coordinating the provision of health-education services and acting as resource people in health education" [7].
Many health-education interventions for hemodialysis patients have been implemented, covering various themes such as physical exercise, medication adherence, and nutrition.Systematic reviews have been conducted on the impact of education in general [8] and specific themes [9].However, to date, no review has specifically examined the impact of nutrition education on hemodialysis patients.
The specific objective of this review was to assess the impact of nutrition education on patients undergoing hemodialysis.This systematic review aimed to address the following questions:

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Can nutrition education improve outcomes for patients undergoing hemodialysis?• Which health-related outcomes can be modified by nutrition education?

Study Selection and Search Strategy
We conducted a systematic literature search covering the period from 1 January 2013 to 8 September 2023.The search terms were organized into three queries:(1) "health education AND hemodialysis"; (2) "patient education AND hemodialysis"; (3) "lifestyle AND hemodialysis".Additionally, for the period from 1 January 2013 to the end of 2023, we included the queries: (1) "health education AND haemodialysis"; (2) "patient education AND haemodialysis"; (3) "Self care AND haemodialysis" in two databases (PubMed and ScienceDirect).The chosen timeframe spanned 11 years to ensure the inclusion of as many recent studies as possible.The search strategy was agreed upon by all the authors, who brought diverse expertise in nursing, public health, and biology.
The flow diagram (Figure 1) illustrates the search strategy, detailing all study selection and elimination stages.
This review is registered in PROSPERO with ID CRD42023460681 and respects the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines [10] (See PRISMA 2020 checklist in supplementary materials).

Inclusion and Exclusion Criteria
Studies, regardless of the language of publication and the study design (i.e., quantitative or qualitative), were excluded if they exhibited the following characteristics: a.
Research does not belong to the filter used (research articles, clinical trials, randomized controlled trials).b.
Design or protocol of article intervention, reports, reports of workshops, and case reports.c.
Population concerned by the education programs not undergoing hemodialysis.d.
The educational intervention does not include nutrition education.e.
Experience of a specific diet trial or comparison between diets.
In the second stage of selection, the remaining articles were downloaded and reviewed in their entirety.Studies were excluded if educational interventions were mixed with other interventions without separate results.

Inclusion and Exclusion Criteria
Studies, regardless of the language of publication and the study design (i.e., quantitative or qualitative), were excluded if they exhibited the following characteristics: In the second stage of selection, the remaining articles were downloaded and reviewed in their entirety.Studies were excluded if educational interventions were mixed with other interventions without separate results.

Data Extraction and Quality Assessment
Studies were independently selected and reviewed by two of the authors (O.M. and B.A.) based on predefined eligibility criteria.RIS files downloaded according to the 6 requests were transferred to the Rayyan platform, a recommended screening system for literature reviews and systematic reviews [11], to eliminate items not meeting the first initial screening criteria.Complete data extraction was conducted when the intervention focused

Data Extraction and Quality Assessment
Studies were independently selected and reviewed by two of the authors (O.M. and B.A.) based on predefined eligibility criteria.RIS files downloaded according to the 6 requests were transferred to the Rayyan platform, a recommended screening system for literature reviews and systematic reviews [11], to eliminate items not meeting the first initial screening criteria.Complete data extraction was conducted when the intervention focused solely on nutrition education.However, in cases where interventions were multidisciplinary and outcomes were separated, only the data related to the nutrition component were extracted, ensuring that they were not influenced by other interventions.
For example, in the case of interventions involving nutrition education and phosphate binder education, data on serum phosphate levels were excluded, as it was unclear which intervention influenced this parameter.However, we did include interventions containing brief education on medication, or assisted by personalized food plans as part of nutrition education.To address the research questions, the results of the selected studies were categorized into several sections that were aligned with the studies' objectives.The outcomes were either compared between pre-and post-intervention within the same group or between intervention and control groups (with or without randomization).
Two authors (M.O. and A.B.) participated in assessing the methodological quality of the included articles using two tools: the JBI Critical Appraisal Checklist for Case Series (10 items) and The Quantitative Study Quality Assessment Tool Rating (31 items).Details of the quality assessment are provided in Supplementary Materials.

Results
The systematic search yielded 8330 articles (Figure 1), of which 3686 duplicates were removed.Following title and abstract screening, 66 articles were selected for full review, of which 2 full texts were not found, although it is highly likely that they would not have been included, having read the abstract.After a full-text review and quality assessment, 41 articles were ultimately included for analysis.
Among the 41 included studies (Table 1), a significant proportion were conducted in Asia (n = 23), followed by South America (n = 6), North America (n = 5), Europe (n = 3), Africa (n = 2), and Oceania (n = 1).Notably, one study was conducted across four different continents.Regarding study design, 51.2% of the studies were randomized controlled trials.Most studies (75.6%) were conducted in hemodialysis units, dialysis centers, nephrological units, and clinics, and 22% were carried out in hospitals or teaching hospitals.The total sample size of patients included in the final analysis was 5243.In terms of publication dates, 43.9%of the studies were published between 2013 and 2018, with the remaining studies published up to 2023.Table 2 provides a detailed overview of each study's aims and relevant results.Patients should be able to recognize the importance of the composition of certain dietary ratios and the implementation of healthy cooking methods to achieve optimal efficacy.
Nutritional education has proven effective in improving hemodialysis patients' knowledge in various areas, as demonstrated by the results of several studies in this review.Significant improvement was observed in nutritional and dietary knowledge scores [16,21,[24][25][26]30,33,51], as well as knowledge of fluid control [23,24].
The clinical, behavioral, and biological manifestations of these educational interventions will be covered in the following sections.

Impact of Nutrition Education on Hemodialysis Patient Behavior/Attitude Change
With the emergence of new diseases associated with longevity and lifestyle factors, the biomedical model has been superseded by models linked to health psychology.These models enable the description of behavioral changes and the development of targeted prevention interventions across primary to tertiary [53].According to the results of certain studies reviewed, dietary behavior has shown significant movement when associated with nutritional education [18,[21][22][23]32,33].

Effect of Nutrition Education on Weight Change
One of the major challenges encountered by hemodialysis patients is interdialytic weight gain, which serves as an indicator of higher pre-dialytic blood pressure, nutrition, and survival in hemodialysis (HD) patients [54].In this review, nutritional education, particularly concerning fluid restriction and control, has demonstrated satisfactory outcomes in reducing IDWG [13,19,23,43] and achieving the ideal percentage of weight loss [34].Furthermore, when combining nutrition education with cognitive behavioral therapy, positive results were observed in terms of reducing IDWG [44].

Effect of Nutrition Education on Malnutrition Inflammation Status
Inflammation and protein-energy malnutrition (PEM) are common and often concurrent conditions among patients undergoing hemodialysis [55].This review demonstrated that the implementation of nutritional education programs had a beneficial effect on the malnutrition inflammation score [22].

Effect of Nutrition Education on Cost of Care
People afflicted with chronic kidney disease are at a greater risk of fatal complications, leading to elevated costs for both patients and healthcare institutions.However, following nutritional interventions has been associated with a lower length of hospital stay [31] and reduced direct costs [35].
3.1.8.Effect of Nutrition Education on the Quality of Life of Hemodialysis Patients Quality of life is a crucial health outcome and represents the ultimate goal of all health interventions [56].Nutrition education has demonstrated this in two studies included in this review by increasing the quality-of-life score [26,29].

Discussion
After extracting and analyzing the results of the selected studies, the contribution of nutrition education has been limited to nine general themes (knowledge, patient behavior/attitude change, weight change, malnutrition inflammation status, dietary intake, adherence to dietary recommendations, quality of life of hemodialysis patients, and biological markers).
Compared to pre-nutritional education, participants showed increased scores in both the knowledge component of fluid control and dietary restrictions/limitations.Similar findings were reported in a study, which concluded that diabetes patients' knowledge and practices about nutrition were improved by nutritional and eating education.This best practice empowered them to control their blood glucose levels effectively [58].
In terms of cost of care, nutrition education was less expensive than other interventions, which is in line with the results of a nutrition education program for reducing childhood obesity, whose findings show that the intervention seems to be both effective and costeffective [59].
A positive change has also been observed in the interdialytic weight gain (IDWG) level, with reductions achieved and satisfactory results obtained.In comparison to another study, dietary advice and food fortification led to weight gain and improved outcomes during and after the intervention period in nutritionally vulnerable outpatients with chronic obstructive pulmonary disease [60].These findings demonstrate that targeted weight goals can be achieved through nutrition education.Furthermore, nutritional education has kept the level of inflammatory malnutrition stable and has increased patients' quality of life.This finding aligns with results indicating that a nutrition education program significantly improved the quality of life of adults living with HIV [61].
In several studies included in this review, regression was recorded in serum phosphorus, potassium, sodium, and creatinine, as well as an increase in serum protein.Addition-ally, the effectiveness of nutritional education in improving biological markers was also observed in diabetic patients by reducing HB1AC and BMI [62].
Compared with other systematic reviews, a review of 43 studies found that school student's health education improved their knowledge, attitudes, perceptions, and behaviors related to physical activity and nutrition [63].Another review comprising 6 studies concluded that nutrition education among Indigenous Australians contributed to the reduction of anthropometric factors and biochemical risks associated with chronic diseases [64].
According to the findings of another analysis, teaching programs focused on physical activity and nutrition may effectively assist African Americans in achieving clinically meaningful results [65].Older individuals who modify their diets through dietetic education or have access to more healthful meal services could be able to obtain better-quality food [66].
Another limitation of this review is the potential for expanding the number of search databases, which could lead to the inclusion of additional studies.
The provision of care for hemodialysis patients represents a substantial burden, affecting patients, families, and healthcare institutions alike.In this context, health education has demonstrated considerable efficacy across multiple domains.
Nevertheless, patient education in hemodialysis encounters various obstacles, particularly related to commitment and adherence to restrictions.Among these challenges, the psychological state of patients represents a significant hurdle, with a notably high prevalence of depression observed [67].Depression has been linked to suboptimal adherence to medication regimens [68,69], as well as dietary non-adherence [70].In this regard, further studies using psychological models need to be conducted to address the issue of depression in hemodialysis patients, particularly those from lower socio-economic backgrounds or underdeveloped countries.

Conclusions
Our study empirically confirmed the positive impact of nutrition education on hemodialysis patients, addressing several critical aspects.These findings underscore the importance of healthcare providers incorporating nutrition education into the standard treatment for hemodialysis patients.
While the results of this review underscore the significance of nutrition education for hemodialysis patients, it is essential to recognize that comprehensive care extends beyond nutrition alone.Healthcare providers must adopt a holistic approach to achieve optimal outcomes.Furthermore, this review provides valuable insights into the precise impact of nutrition education on hemodialysis patients, incorporating contemporary methods rooted in behavior change theories and leveraging innovative technological tools.
In this regard, healthcare providers are tasked with implementing nutritional educational interventions tailored to optimize benefits for individuals affected by this condition, taking into account the availability of educational resources within their respective healthcare establishments.

Figure 1 .
Figure 1.PRISMA flow chart of the selection process.
a. Research does not belong to the filter used (research articles, clinical trials, randomized controlled trials).b.Design or protocol of article intervention, reports, reports of workshops, and case reports.c.Population concerned by the education programs not undergoing hemodialysis.d.The educational intervention does not include nutrition education.e. Experience of a specific diet trial or comparison between diets.

Figure 1 .
Figure 1.PRISMA flow chart of the selection process.

Table 2 .
Objectives and relevant results of selected studies (n = 41).

Table 2 .
Cont. .1.Areas of Action Studied, with Results Achieved in Each Study: (All Reported Changes Are Statistically Significant) 3.1.1.Impact of Nutrition Education on Hemodialysis Patient Knowledge 3