Background

Renal failure, one of the most common diseases worldwide, is a progressive disease that can lead to complete loss of kidney function and requires renal replacement therapy (RRT) [1]. This treatment includes kidney transplant and dialysis. Dialysis, a common type of RRT, can include hemodialysis (HD), peritoneal dialysis, and hemofiltration [2]. The type of dialysis is chosen based on the patient’s condition and availability of the dialysis apparatus at medical centers. HD is the most common type of dialysis performed in Iran [3]. Therefore, it is important to pay greater attention to different aspects of HD in our country.

It is well known that dialysis impairs patients’ quality of life and imposes a great economic and social burden on patients and the health care system. Therefore, additional care is required to improve dialysis efficiency and improve the patient outcomes; one of the important steps in this regard is adherence to a healthy diet that can reduce weight and edema, improve the control status of the underlying disease, and decrease the need for phosphate binder therapy. These recommendations include controlling the intake of potassium, phosphorus, sodium, and fluids; consuming of fresh foods; restricting the consumption of pasta, rice, and sweet potato, and choosing foods with less than 400 mg sodium/100 g [4, 5]. Although the guidelines clearly define the dietary recommendations, many patients have problems adhering to a healthy diet. Therefore, education on dietary and fluid compliance is required to reduce the risk of complications [6] and improve quality of life [7]. It is important to design additional strategies to educate patients about healthy diets and improve their adherence to their diet. The educational strategies suggested include pamphlets and/or booklets, nurse-led telephone follow-up, mobile applications or text messaging [8, 9].

However, using these educational materials requires adequate literacy to be able to read and therefore is not appropriate for illiterate patients or those who cannot read Persian. Patients with a lower educational level have a greater risk of limited health literacy and thus greater risk of death [10]. Some have suggested that video-based education during dialysis is as effective as face-to-face education [11, 12]. It has been shown that video-based education presented during dialysis can also improve patients’ quality of life [13, 14]. To evaluate the efficacy of video intervention, it is important to investigate changes in electrolytes and serum parameters. Therefore, in the present study, we designed an educational video, and played it at each session of HD for the patients; then we compared its effect on the level of knowledge, attitude, performance and metabolic control of the patients.

Methods

This study is an interventional study with a one-year follow-up. In this study, we have compared the level of knowledge, attitude, performance and metabolic control of patients before and after showing an educational video about healthy nutrition in patients on hemodialysis. All the patients who were receiving hemodialysis at Ashrafi-Esfahani Medical Center from May 1, 2018 to June 30, 2019 were enrolled in the study ( N = 190). The inclusion criteria for patients were as follow: Aged 18–70 years, underwent hemodialysis 2–3 times a week for at least 3–4 h each at the study center.

The exclusion criteria for patients were as follow: known psychological problems, inability to understand Persian language speech or inability to attend to the video and/or not regularly referred for the HD sessions.

The researcher explained the study objectives to the eligible patients and asked them to read and sign the written informed consent. The participants were enrolled in the study by a nonrandomized (convenient) sampling method (N = 130). The flowchart of the study is given in Fig. 1. After selecting the samples, the initial questionnaire was completed by the project nurse in terms of the basic characteristics and level of awareness of the patients before the intervention and examinations. The first clinical examination was performed in the fasting state before hemodialysis, and other evaluations were performed after the completion of hemodialysis. Initially, 10 cc of venous blood was taken from the patient after 12 h of fasting to measure the serum levels of sodium (Na), potassium (K), calcium (Ca), phosphorus (P), magnesium (Mg), blood urea nitrogen (BUN), creatinine (Cr), albumin (Alb), hemoglobin (Hb), hematocrit (Hct), parathyroid hormone (PTH), cholesterol (Chol), triglyceride (TG), HDL-C (high density lipoprotein- cholesterol; urea and creatinine in the urine for dialysis efficacy (Kt/V), and URR (urine filtration rate). All the tests were performed on the same day.

Then, the training video was played 7 times (once a week in the first month, once every two weeks in the second month, and once in the third month) during hemodialysis for the patients. The questionnaire was completed again in terms of knowledge and attitudes and blood and urine tests were repeated at the end of the third and 12th months.

Height was measured with a metal stadiometer (0.5 cm accuracy) while the participants were in a standing position. Blood pressure was measured after 15 min of rest with a standard mercury sphygmomanometer from the right hand while the patients were lying down before dialysis in a fasting state.

The educational video was prepared by Dr. Yasari (nephrologist) based on the Guideline of the Iranian Society of Kidney Disease (ISKD) as a PowerPoint show [15]. This PowerPoint show lasts 20 min. First, a video of the doctor’s lecture on the importance of nutrition in the metabolic control of hemodialysis patients was prepared and attached to PowerPoint. Then, the graphic slides were prepared with respect to the principles of proper nutrition in patients on hemodialysis and healthy or harmful foods. The doctor’s speech was added to the slides which were broadcast during the slide show. In addition, the important principles of healthy nutrition were reviewed by Dr. Yasari as another attached video in last slide.

Before playing the video, the researchers checked the patients’ level of awareness of the proper diet content (knowledge). They asked the participants what ingredients in the diet are important for the health of hemodialysis patients. At this stage, those who pointed out the restriction of salt, liquid, fat, protein and phosphorus consumption and increased consumption of iron and calcium were considered people with appropriate knowledge.

After showing the educational video, the researcher asked the participants the following questions to check the level of knowledge of the patients about proper diet:

Which food contains high amounts of sodium, potassium, calcium, phosphorus and protein? How can you limit the consumption of liquids, salt (sodium), potassium, phosphorus and protein? What foods can increase the amount of calcium and iron?

To investigate patient attitudes, the researchers prepared a list of various healthy or unhealthy food items for each meal for hemodialysis patients and suggested this list to the participants as a breakfast, lunch or dinner menu. Then the participants were asked to choose a suitable diet from this hypothetical menu. A participant who chose a healthy diet was recorded as having a positive attitude, and a participant who chose an inappropriate diet was recorded as having a negative attitude.

At the end of the study, serum parameters and dialysis adequacy indicators were considered criteria for evaluating patient performance.

Serum levels of Na, K, Ca, P, and Mg were measured using BT3000 spectrophotometric chemical analysis. Serum urea and creatinine levels were measured by the Jaffe kinetic colorimetric method with an automatic analyzer (Vital Scientific, Spankeren, Netherland) using commercial kits (Pars Azmoun Company, Tehran, Iran). The serum Alb level was measured by an autoanalysis machine (COBASMIRA, ROCH, France) with the “Albumin and Protein Kit” (Biochem Company, Iran). Hb and Hct were measured with a fully automatic analyzer (Sysmex KX-21NTM, Japan). Serum levels of vitamin D and intact PTH were measured with an enzyme-linked immunosorbent assay (ELISA) kit. FBS was measured by the glucose oxidase method, cholesterol by the cholesterol oxidase method, triglycerides by the glycerol phosphatoxidase method and HDL-C by the direct enzyme method. Biosystem kits (S.A.casta Brava 3, Barcelona, Spain) were used for serum lipid profiles in the autoanalyzer (Biosystem A25, Spain). The devices were calibrated every day.

The normal ranges of these laboratory parameters in adults are as follows: Na, 135–145 meq/L; K, 3.5–5.3 meq/L; alcium, 8.6–10.3 mg/dl; P, 2.5-5 mg/dl; Mg, 1.5–2.6 mg/dl; Cr,0.5–1.5; Urea, 10–50 mg/dl; Alb,3.5–4.5 g/l; Hb,12.3–15.3 g/dl for women and 14–17.5 g/dl for men; Hct, 36-44.6% for women and 41.5–50.4% for men; FBS, 70–100 mg/dl; Cholesterol, up to 200 mg/dl; Triglyceride, up to 200 mg/dl and HDL- Cholesterol, more than 34 mg/dl.

The normal PTH level was less than 65 pg/ml.

To check the adequacy of dialysis, kt/v was calculated with nephrology calculator [16].

The URR is calculated as [17]:

URR=[(predialysis BUN − postdialysis BUN) / predialysis BUN] ×100%.

The serum levels of sodium, phosphorus, hemoglobin, etc. were measured and compared with those measured before the study.

The protocol of the study was approved by the Ethics Committee of the National Research Institute of Tuberculosis and Lung Disease - Shahid Beheshti University of Medical Sciences (approval ID: IR.SBMU.NRITLD.REC.1399.206) [18]. This trial is registered in Iran clinical trials with ID: IRCT2016082229481N1.

Statistical analysis

The results were presented as the mean ± standard deviation (SD) for quantitative variables. The one–sample Kolmogorov–Smirnov test was used to determine the normality of the distribution of the data and Levene’s test was used to test the equality of variances. Continuous variables were compared using t-tests or Mann-Whitney U tests, whenever the data did not appear to have a normal distribution or when the assumption of equal variance was violated across the study groups. The trends of the changes in the serum parameters over the 12 months are depicted in the figures. The mean differences in the last value (month 12) and baseline value (pre-intervention) were calculated and compared using paired sample t-tests. For the statistical analysis, the statistical software SPSS (IBM SPSS Statistics for Windows version 21.0, IBM Corp.) was used. P values < 0.05 were considered to indicate statistical significance.

Results

In this interventional study, 130 people were eligible to participate (see Fig. 1).

In terms of age, 8%, 55% and 37% of people were in the age groups of 20-39.9, 40-59.9 and more than 60 years, respectively. Seventy-seven people (60%) were male. The patients underwent hemodialysis 3.98 times a week for 3.85 h each, and the average weight gain during the dialysis intervals was 2.4 kg. About half of the patients had urinary excretion, edema and muscle cramps. In terms of vein access routes, 2%, 35%, 61% and 2% of patients had temporary catheters, permanent catheters, arteriovenous fistulas and grafts, respectively. Thirty-four, 23, 36 and 8% of patients were illiterate, had a primary education, had a diploma and had a higher education, respectively. In terms of underlying disease, 95% of the patients had diabetes, hypertension or both. 10% of people do not take any of their medications.

Fig. 1
figure 1

Study fellow chart

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Less than 20% of the participants were aware of the various components of the suitable diet for hemodialysis patients (10%, 16%, 18%, 19% and 19% in terms of phosphorus, potassium, fluids, sodium and protein food content, respectively) at baseline. After watching the educational video, the level of awareness of the patients about the food content about reducing the consumption of sodium, potassium, protein and phosphorus in the diet increased by 5%, 22%, 20%, 34% and 20%, respectively(P-Value < 0.05 for K, P, Protein and fluid). Please see Table 1.

Table 1 The level of awareness of patients about the content of food by ingredients
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To check the attitudes of the patients, they were asked to choose their food from a hypothetical food list (containing healthy and unhealthy food for dialysis patients) for three meals: breakfast, lunch and dinner. Only 10% of patients select healthy foods before intervention. After watching the educational video, 25, 14 and 47% of patients chose healthy food for breakfast, lunch and dinner, respectively. The selection of healthy foods from the list of suggested foods increased significantly after the intervention (10% vs. 26%; P-Value < 0.05).

In order to check the performance of the people, the level of serum parameters and the adequacy of dialysis were checked. After the intervention, the mean serum levels of sodium, phosphorus, iPTH (intact PTH) and creatinine and pre or postdialysis urea decreased and the mean serum levels of calcium, hemoglobin and hematocrit and the KTV of urea increased significantly. After the intervention, the reduction in the average serum urea after dialysis (the difference between the serum urea levels before and after dialysis) increased compared to that before the intervention (Table 2).

Table 2 Serum levels of blood parameters and dialysis adequacy before and after intervention in the participants
Full size table

Discussion

In this interventional study, we have compared metabolic control of patients before and after showing an educational video about healthy nutrition in patients on hemodialysis. Less than a fifth of patients were aware of the various components of the suitable diet for hemodialysis patients. The awareness of patients about healthy diet increased by 20% after watching the educational video. The attitude of the patients was checked by choosing healthy food from a hypothetical menu. The selection of healthy foods increased significantly after the intervention (10% vs. 26%). The results of the present study revealed significant changes in the serum parameters of the study group after video presentation. After the intervention, the mean serum levels of sodium, phosphorus, iPTH and creatinine and pre- or post-dialysis urea decreased and the mean serum levels of calcium, hemoglobin and hematocrit and the Kt/V of urea increased significantly.

In this study, after watching the educational video, the level of awareness of the patients about healthy diet increased twice and positive attitude change was seen in a quarter of the patients. Others have also referred to the significance of knowledge of patients undergoing hemodialysis about dietary recommendations and the influence of educating patients about these instructions [6, 7]. In the study of Monaghi et al., face-to-face training was more effective than non-face-to-face training. They showed that with the increase in the frequency of training sessions, the patients’ attitudes changed more positively [19]. However, face-to-face education requires a separate room for performance, educated staff to present the information to each patient, and the patient should attend the class/presentation [7]. These factors may prevent education for all patients. Video presentation is an easy method for patients; first, the educator presents it once and no additional time is required to present the information to each patient separately; only, the recorded video is presented for all patients. This will also homogenize the information presented to patients. Furthermore, there is no need for the patient to schedule additional time for the presentation, as the video is presented to the patient during hemodialysis, when the patient has to stay under a dialysis device for hours. In addition to these benefits, comparisons of face-to-face education with video presentations revealed similar changes in biochemical parameters [6], adherence to the instructions [7, 12], and quality of life of patients [14, 20] under hemodialysis.

The results of the present study showed that after the intervention, the Na, Ca, and Chol levels and Kt/V ratio increased, while the P, Cr, Htc, PTH and BUN levels decreased. In the study by Baraz and colleagues, the video presentation revealed a significant increase in mean Ca levels (from 8.63 to 9.62 mg/dl; P = 0.001) and a decrease in P (from 6.25 to 5.16 mg/dl; P = 0.007), and uric acid (from 7.17 to 6.32 mg/dl; P = 0.036) but no significant changes in Cr, Na, K, BUN or Alb [6]. The increase in Ca and decrease in P values, documented in this study are consistent with the results of these studies. In a recently published study in Iran, a mobile application was provided to patients and the results showed significantly decreased mean K, P, TC/TG, and ferritin levels in this group of patients [21]; these results are consistent with the results presented in the present study, considering the decrease in P levels. According to the evidence, noncompliance with P can result in important adverse events, such as bone demineralization and renal bone disease, in the long run; as its effect presents late, the patient may not pay sufficient attention to this biochemical agent, but he/she may suffer from its long-term influence [22]. Therefore, it is important to notify patients about controlled dietary P loads by avoiding foods that are rich in P or have high P/protein, and processed food with P-containing preservatives [22, 23].

Nonadherence to Na has also been suggested to be an important factor in patients under hemodialysis, as excessive Na intake thirsts patients, which leads to increased fluid intake and interdialytic weight gain; therefore, it is important to restrict Na intake in these patients [23,24,25]. The results of the present study showed that the mean Na value was greater after the intervention but the difference was not significant. Similarly, others have reported no difference in Na levels according to dietary education [26]. An increase in the serum levels of total Chol in the present study also showed that the patients did not undergo close observation of their dietary regimen; this will put the patients at risk of complications. Therefore, more emphasis is required on the salt and fat intake of patients undergoing hemodialysis in educational programs or other strategies used for improving patients’ knowledge and awareness.

Anemia is a common complication in patients under hemodialysis and increases the risk of cerebrovascular and cardiovascular diseases, infection and hospitalization; therefore, it is important to maintain a target-range Hb level in patients under hemodialysis [27]. Anemia may be the result of secondary hyperparathyroidism, mediated via multiple pathways, such as bone-derived fibroblast growth factor 23 [28, 29]. The results of the present study showed that Hb levels improved and PTH levels decreased, which is in line with the results of studies suggesting an adverse association between Hb and PTH levels [28, 29]. Therefore, it is important to pay attention to these serum parameters in patients undergoing hemodialysis.

Adequacy of hemodialysis, Kt/V, is an important factor in the outcome of patients undergoing hemodialysis, as it is associated with patient mortality, anemia, and hypoalbuminemia. In the present study, Kt/V increased significantly after the intervention, which may be due to the influence of diet education on these patients; however, studying the mean difference was not significant. Other researchers have also reported no difference in the mean Kt/V before and after repeated educational programs [30], which is consistent with the results of the present study.

One of the limitations of the present study was the lack of a control group to compare the results of this intervention with those of a group that did not receive this intervention to observe the pure effect of the intervention. Another limitation of the present study was related to the nonrandomized enrollment of patients in the study and the selection of patients from one medical center; these limitations increase the chance of confounders affecting the study results.

Conclusion

The present study showed that the educational video was effective for assessing metabolic/serum parameters in patients on hemodialysis and can be an appropriate option for improving the knowledge/awareness of patients under hemodialysis and their dietary compliance. Therefore, it is suggested to consider the inclusion of a video presentation in the strategies planned for patients undergoing hemodialysis.