Introduction

Chronic kidney disease (CKD) is a global public health issue that affects many people around the world. Of the estimated 14.4% of adults in the United States who have CKD, up to 90% are unaware of their disease (U.S. Renal Data System, 2021). A study on 3,713 patients with Stage 3–4 CKD categorized the sample into four risk levels for renal failure within 5 years: minimum risk (< 2%), low risk (2%–4%), moderate risk (5%–14%), and high risk (≥ 15%). The study concluded that up to 51% of patients in the moderate- and high-risk populations were unaware of their CKD. Patients have a much lower awareness of CKD than of diabetes and hypertension (Chu et al., 2020). However, the onset and progression of a chronic disease tend to be slow, and patients with CKD often have one or more concurrent chronic diseases (Elliott et al., 2020). The progression of chronic disease also affects the mental health of patients. Studies have shown that up to 75.5% of patients with CKD experience depression, which in turn compromises their quality of life (QOL; Kunwar et al., 2020). This emphasizes the importance of aggressive screening and early intervention.

The definition of CKD includes all individuals with an estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m2 over a 3-month period, an albumin-to-creatinine ratio ≥ 30 mg/g, or other markers of kidney damage regardless of kidney injury status. In those with CKD, the kidneys do not function properly and treatment, for example, kidney transplantation, is required to avoid kidney failure (National Kidney Foundation, 2022). Therefore, delaying CKD progression is the key focus of medical care. In Taiwan, since the enactment of the National Health Insurance's Healthcare and Health Education for Pre-End Stage Renal Disease Patients Program in 2003, the high-risk population with CKD (patients in Stages 3b–5) has been subject to case management and receives care from a professional medical team responsible for assessing each patient's self-care and self-management abilities. Furthermore, this team follows up on patient health status to help maintain residual renal function. As part of the program, the CKD Clinical Practice Guidance recommends initiation of a low-protein diet (0.6–0.8 g/kg a day) and ketogenic amino acid treatment for patients with Stage 3 CKD to reduce kidney damage caused by nitrogenous wastes and delay dialysis or death (Xu, 2015).

Health literacy is a relatively new field of research in the area of medicine and health. Different age groups require different health literacy programs to empower them to implement beneficial health behaviors (Quaglio et al., 2017). A systematic review by Sørensen et al. (2012) defined health literacy as the “knowledge, motivation, and competencies of accessing, understanding, appraising, and using health-related information within the healthcare, disease prevention and health promotion setting in daily life to make judgment and decisions in order to maintain or improve the overall QOL.” Therefore, health literacy influences self-care efficacy and disease prognosis. Lack of health literacy has been reported in 17.7% of patients with Stage 1–5 CKD (Schrauben et al., 2020), and low or absent health literacy has been reported in 22.5% of patients with Stage 3–4 CKD (Hanpaiboon & Pratoomsoot, 2019). Wei et al. (2017) has evaluated the validity of the Mandarin Multidimensional Health Literacy Questionnaire (MMHLQ) on a sample of 2,394 adults in Taiwan, finding the highest score in the domain of “understanding health information,” followed by “accessing health information,” “communication and interaction,” “applying health information,” and “appraising health information.” Factors that affect health literacy include age, gender, educational level, marital status, spouse cohabitation status, family income, CKD stage, duration of CKD, and number of comorbidities (Y.-C. Chen et al., 2018; Hanpaiboon & Pratoomsoot, 2019; Wong et al., 2018). Patients with higher health literacy show better self-care behaviors (Schrauben et al., 2020).

Patients with CKD tend to experience depression because they are forced to attend numerous hospital visits and face complex treatment plans, drug side effects, dietary restrictions, and uncontrollable clinical symptoms as their disease progresses (S. F. V. Wu et al., 2018). The prevalence of depression is related to CKD stage. A meta-analysis of 22 studies that investigated the correlation between depression and death in patients with CKD reported an average depression prevalence of 27.4% in predialysis patients with CKD (Palmer et al., 2013). Patients with CKD experiencing depression exhibit poor compliance to drug treatment and poor QOL, resulting in increased utilization of medical resources and higher rates of morbidity and mortality (Palmer et al., 2013).

A study conducted by S. F. V. Wu et al. (2018) applied an innovative health education program promoting self-management in a sample of patients with Stage 3b–5 CKD. The program delivered one 100-minute session per week for 4 weeks, and the participants were followed up for 3 months. Outcomes included significantly improved blood urea, nitrogen, and creatinine; reduced depression; and higher self-efficiency and self-management. However, the intervention had no effect on eGFR. Wang et al. (2018) conducted a cross-sectional study to compare the effect of participation in a comprehensive healthcare program on self-care behaviors and kidney function in patients with CKD. The results revealed a slower rate of deterioration in kidney function and better self-management behaviors in patients participating in the healthcare program. Machida et al. (2019) studied the effects of a 1-week inpatient education program on kidney function in patients with Stage 3–5 CKD. The patients were followed from 6 months before hospitalization to 24 months after discharge. Implementation of the program delayed kidney function deterioration during the 2-year observation period, especially in patients with low proteinuria (urinary protein < 0.5 g/gCr). Thus, the authors recommended the program be initiated in patients with low proteinuria. A randomized clinical trial conducted by Lin et al. (2021) investigated patients with Stage 1–3a CKD, with the study group receiving routine care and health coaching for 6 weeks in addition to 12 months of postintervention follow-up. The findings indicate health coaching improves QOL, self-management, patient activation, and self-efficiency.

On the basis of the evidence in the literature, health education programs are beneficial to patients with CKD. Health literacy can influence self-care behaviors and renal function in these patients. However, there is a lack of rigorous research on the impact of health literacy on the psychology of patients with CKD. Therefore, the aim of this study was to investigate patients with Stage 3–4 CKD (the largest group in Taiwan's Pre-End Stage Renal Disease Patients Program), develop a health literacy education program (HLEP), and evaluate the effect of this program on participants' mental health and renal function. This study addressed the following research hypotheses:

Patients with CKD who participate in the HLEP will have increased health literacy compared their nonparticipant peers. Patients with CKD who participate in the HLEP will have improved depression compared their nonparticipant peers. Patients with CKD who participate in the HLEP will have improved renal function compared their nonparticipant peers. Methods Design

The study design was a single-center, two-group, single-blinded, randomized controlled trial with a repeated-measures design. The participants were randomized into either the HLEP with multidisciplinary care (experimental) group (EG) or the multidisciplinary care (control) group (CG). Block randomization with 1:1 allocation was conducted using a computer-generated sequence and was performed by one of the authors not involved in screening, patient recruitment, clinical care, or data collection using a random number generator. Sequentially numbered, opaque, sealed envelopes were used to conceal the sequence until the interventions were assigned at an outpatient nephrology clinic. Patients were followed for 6 months. Data were collected before health education (T1) and at 3 months (T2) and 6 months (T3) after completion of the HLEP (Figure 1).

Figure 1.:

Research Design FlowchartNote. T1: demographic characteristics, Mandarin Multidimensional Health Literacy Questionnaire (MMHLQ), Beck Depression Inventory-II (BDI-II), and estimated glomerular filtration rate (eGFR) were collected. T2 and T3: MMHLQ, BDI-II, and eGFR were collected.

Setting

The participants in this study were conveniently sampled from the nephrology outpatient clinic of a 988-bed regional educational hospital in northern Taiwan.

Participants

Patients who met the selection criteria were recruited. The inclusion criteria were patients aged ≥ 20 years who were able to communicate in Mandarin or Taiwanese, were diagnosed by a nephrologist with Stage 3 or 4 CKD, and had received less than 1 year of comprehensive care. The exclusion criteria included having a cognitive disorder or mental illness (severe depression, schizophrenia), being on routine hemodialysis, or current hospitalization.

Sample Size

Following Wang et al. (2018), minimal sample size was calculated using G*Power V3.1 statistical software with eGFR as the primary efficacy variable (EG: eGFR = 0.072 ± 8.212, n = 118; CG: eGFR = −2.978 ± 8.680, n = 117). The effect size was estimated as 0.36, α was set at .05, and power was set at 0.95. The participants were divided into two groups with three measurements each. The minimum sample size was calculated as 70. Assuming a follow-up loss of 20%, the final sample size was set as 84 (42 per group).

Experimental Intervention and the Control Group

The main components of the HLEP are shown in Table 1. The HLEP included a self-management health education manual and a dietary health education video designed for patients with Stage 3–4 CKD. The health education manual was developed by the researchers based on the Health Literacy Concept and Material Preparation Guide (National Health Insurance Administration, Ministry of Health and Welfare, Taiwan, ROC, 2020) and frequently asked questions from patients and family members. The preliminary review focused on the content and format of the draft, with subsequent revisions made based on comments (Devellis, 2016). Five experts were invited to assess the content validity, with the content validity index assessed in terms of “appropriateness,” “accuracy,” and “readability” as .98, .88, and .95, respectively, on a 5-point Likert scale, with an overall content validity index of .93. The content of the health education manual was edited based on the experts' comments to create the final version. In the interests of portability, the size of the health education manual was designed as 145 mm in length and 210 mm in width with 15 pages. As most of the participants in this study were older adults, the dietary principles were presented in video format. To maximize learning outcomes, an attending physician from the department of nephrology and one of the researchers personally introduced the dietary principles for patients with Stage 3–4 CKD based on the health education manual. Media professionals were hired to produce the video and sound recordings using PhotoImpact and Adobe Audition for conversion to MP3. The video was designed with a minimum of text and used simple words, pictures, cartoon figures, large fonts, and interactive images.

Table 1. - Main Contents of the Health Literacy Education Program Time Main Issue Main Content Day 1 Chronic kidney disease self-management health education manual (one-on-one health education: 20 minutes) ▪ Introduction of kidney function
▪ Chronic kidney disease and stage
▪ Importance of regular medication
▪ Importance of regular exercise
▪ Blood pressure control
▪ Dietary principles for Stage 3–4 CKD Stage 3–4 CKD dietary health education video (10 minutes) ▪ Low protein, enough calories
▪ Dietary principles of potassium restriction
▪ Low-sodium diet
▪ The strategies of blood sugar control and   glycated hemoglobin (HbA1c)
▪ Prevent hyperlipidemia
▪ Dietary limitation
▪ Examples of three-meal recipes and substitutions,   types of low-protein starches Week 5, 9, 13, 17, 21 Telephone consultation (5–10 minutes) ▪ Remind patients to watch health education video   per month
▪ Discuss video content and dietary principles
▪ Encourage patients to ask questions Week 12, 24 Routine outpatient follow-up ▪ Discuss health education content and   blood test value
▪ Clarify patient concerns

Note. CKD = chronic kidney disease.

In the EG, members received one-on-one health education from a study team member with 6 years of experience in kidney disease nursing. The HLEP was delivered using a health education manual in the nephrology outpatient health education classroom. After each session, the participants and their families watched a health education video and were encouraged to ask questions until they fully understood the concepts. In addition, EG participants were taught how to access the videos via their smartphones on YouTube or by scanning a QR code on the cover of the health education manual.

CG participants received routine one-on-one health education from a case manager at the participating hospital who explained the blood analysis results and precautions and distributed an A4-sized health education leaflet.

Data Collection

Data for this study were collected from March 25 to December 18, 2021. The data were collected at three time points: before HLEP implementation (T1) and at 3 months (T2) and 6 months (T3) after HLEP. For participants who were illiterate or had difficulty reading and thus not able to complete the questionnaire independently, a designated staff member explained the questionnaire and assisted them to complete it based on their answers. EG participants received multidisciplinary care, participated in the HLEP, and conducted monthly phone discussions with the researcher about the program's content on the first Monday of each month. CG participants received multidisciplinary care, and their data were collected at the same time points as EG participants.

Ethical Considerations

This study was approved by the research ethics committee of National Taiwan University Hospital Hsinchu Branch (Approval No. 91T-27-0026) before initiation. The investigator explained the study purpose and procedure to the participants before they signed informed consent. The participants were informed they were free to withdraw at any time during the study and that their withdrawal would not affect their treatment or cause any negative impact. The study data were coded and analyzed anonymously.

Instruments Demographic and disease characteristics

The patient characteristics considered in this study included age, gender, educational level, marital status, monthly income, CKD stage, chronic disease history, and duration of treatment in the nephrology department.

Mandarin Multidimensional Health Literacy Questionnaire

The MMHLQ developed specifically for adults in Taiwan by Wei et al. (2017) was used in this study. The 20 items of the MMHLQ assess health information, health information comprehension, health information appraisal, health information application, communication, and interaction using a 4-point scale: 1 = very difficult, 2 = difficult, 3 = easy, and 4 = very easy. Total and subscale scores are converted to a 0–50 range using the equation (Mean − 1) × (50/3), with 0–25 indicating insufficient, 25–33 indicating limited, 33–42 indicating sufficient, and 42–50 indicating excellent level of health literacy. Higher scores on the MMHLQ indicate better health literacy. The internal consistency reliability analysis revealed good internal consistency (Wei et al., 2017), with a Cronbach's alpha of .92 in this study.

Beck Depression Inventory

The 21-item Beck Depression Inventory-II (BDI-II) Chinese version was used in this study to measure depression. Items are scored on a 4-point Likert scale, with 0 = no, 1 = mild, 2 = moderate, and 3 = severe symptoms. The participant chooses the statement in each item that best describes how they felt over the past 2 weeks (including the day of the examination). The total score ranges between 0 and 63, with 0–13 indicating normal emotion, 14–19 indicating mild depression, 20–28 indicating moderate depression, and 29–63 indicating severe depression. The BDI-II is aligned with the diagnostic principles of depression in the Diagnostic and Statistical Manual Disorders, Fourth Edition and thus may be used to determine depression status. The BDI-II has excellent validity (H. Y. Chen, 2000), and the internal consistency Cronbach's α value in this study was .82.

Renal function

In this study, eGFR was used to monitor kidney function. Data were collected from medical records, and eGFR was calculated using the Modification of Diet in Renal Disease simplified equation developed by the Modification of Diet in Renal Disease Study Group (Levey et al., 2007). The participating hospital scheduled visits for the patients every 3 months, and one blood sample was collected based on the guidelines of the comprehensive care program for kidney disease. Blood samples were collected from the patient during the week before the scheduled visit date.

Data Analysis

IBM SPSS Statistics for Windows 20.0 (IBM Inc., Armonk, NY, USA) was used for data archiving and statistical analysis, with results presented as frequency, percentage, mean, and standard deviation. The demographic and disease characteristics were compared between the groups using the χ2 test, independent samples t test, and paired samples t test. The outcome variables, including health literacy, depression, and eGFR, were compared between the two groups using a generalized estimating equation with repeated measures.

Results

Eighty-four participants completed the study (0% attrition), with 42 each in the EG and CG. Age ranged from 30 to 87 years and averaged 65.39 (SD = 11.39) years. No significant differences between the two groups were found in terms of demographic and disease characteristics (Table 2).

Table 2. - Homogeneity Test of Demographic and Clinical Characteristics (N = 84) Variable Overall (N = 84) EG (n = 42) CG (n = 42) χ2 p n % n % n % Gender 0.66 .588  Female 17 20.2 10 23.8 7 16.7  Male 67 79.8 32 76.2 35 83.3 Age, years 2.30 .512  ≤ 64 35 41.7 18 42.9 17 40.5  65–74 33 39.3 16 38.1 17 40.5  ≥ 75 16 19.0 8 19.0 8 19.0 Education 2.69 .260 a  High school and below 55 65.5 24 57.1 31 73.8  Junior college 9 10.7 6 14.3 3 7.1  University and above 20 23.8 12 28.6 8 19.1 Marital status 1.40 .433 a  Not married 7 8.3 2 4.8 5 11.9  Married 77 91.7 40 95.2 37 88.1 Monthly income (NT$) 0.75 .119 a  No 43 51.2 17 40.5 26 61.9  ≤ 20,000 12 14.3 5 11.9 7 16.6  20,001–39,999 12 14.3 7 16.7 5 11.9  40,000–49,999 4 4.8 4 9.5 0 0.0  50,000–59,999 8 9.5 6 14.3 2 4.8  ≥ 60,000 5 5.9 3 7.1 2 4.8 CKD stage 1.93 .381  3a 18 21.4 8 19.0 10 23.8  3b 38 45.2 17 40.4 21 50.0  4 28 33.4 17 40.5 11 26.2 Chronic disease history 1.64 .442 a  1 category 21 25.0 13 31.0 8 19.1  2 categories 36 42.9 17 40.4 19 45.2  ≥ 3 categories 27 32.1 12 28.6 15 35.7 Hypertension 0.66 .415 a  No 17 20.2 10 23.8 7 16.7  Yes 67 79.8 32 76.2 35 83.3 Diabetes 1.20 .274  No 39 46.4 22 52.4 17 40.5  Yes 45 53.6 20 47.6 25 59.5 Gout 0.00 1.000  No 54 64.3 27 64.3 27 64.3  Yes 30 35.7 15 35.7 15 35.7 Albumin (g/dl) 17.71 .314  Normal (3.5–5.7) 81 96.4 41 97.6 40 95.2  Abnormal (< 3.5, > 5.7) 3 3.6 1 2.4 2 4.8 Proteinuria (g/dl) 80.00 .447  Normal (≤ 150) 23 27.6 9 21.6 14 33.6  Abnormal (> 150) 61 72.4 33 78.4 28 66.4

Note. EG = experimental group; CG = control group; CKD = chronic kidney disease.

a Fisher's exact test.

As shown in Table 3, no significant differences between the two groups were found in terms of health literacy, depression, or eGFR before the HLEP intervention. The average MMHLQ score of the participants before health education was categorized as “limited.” The highest scores for both groups were reported in the domain of “understanding health information,” followed by “communication and interaction,” “applying health information,” “appraising health information,” and “accessing health information.” In terms of depression, only 16 (19.1%) participants reported depression before the intervention, including 15 (17.9%) with mild and one (1.2%) with severe depression. There were 31, 10, 0, and 1 participant in the EG and 37, 5, 0, and 0 participants in the CG with normal, mild, moderate, and severe depression, respectively, with no significant between-group difference in depression noted (χ2 = 10.129, p = .928). The MMHLQ, depression, and eGFR scores over time for the two groups are presented in Figure 2, and a summary of the GEE results for MMHLQ, depression, and eGFR is shown in Table 4. A model with an exchangeable correlation matrix and model-based estimates of variance was used. After adjusting for age and gender, relationships between health literacy and, respectively, time, group, and Time × Group interaction were explored. The model showed the time effect as more significant for T2 and T3 compared with T1. Trend differences (interactions between time and group) revealed significant differences in health literacy at T2, indicating time-dependent growth effects. Trend differences revealed significant improvements in depression scores for the EG at T2 and T3, indicating time-dependent growth effects. In terms of eGFR, the time effect was more significant at T3 compared with T1. Trend differences revealed a significant increase in eGFR for the EG at T3, indicating time-dependent growth effects. The overall mean eGFR at pretest (T1) was 35.96 (SD = 11.53) ml/min per 1.73 m2 and, at T3, had increased in the EG from 34.96 ml/min per 1.73 m2 to 38.83 ml/min per 1.73 m2 and decreased in the CG from 37.16 ml/min per 1.73 m2 to 35.35 ml/min per 1.73 m2.

Table 3. - Homogeneity Test of MMHLQ, Depression, and eGFR (N = 84) Variable EG (n = 42) CG (n = 42) t p Mean SD Mean SD MMHLQ/overall 30.06 5.78 28.06 7.27 −1.40 .166  Accessing health information 25.60 11.55 23.61 12.47 −0.76 .452  Understanding health information 35.12 6.96 34.92 8.73 −0.12 .909  Appraising health information 27.27 6.96 24.70 8.60 −1.51 .135  Applying health information 29.66 7.71 26.69 10.62 −1.47 .145  Communication and interaction 32.64 6.03 30.36 6.39 −1.68 .096 Depression 9.29 6.99 7.12 4.72 −1.67 .100 eGFR (ml/min per 1.73 m2) 34.76 12.69 37.16 10.27 0.88 .384