The mediating role of depression in the relationship between fatigue and sleep quality in kidney transplant patients

doi:10.21203/rs.3.rs-4885290/v1

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The mediating role of depression in the relationship between fatigue and sleep quality in kidney transplant patients

https://doi.org/10.21203/rs.3.rs-4885290/v1

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Objective: The purpose of this study was to explore the mediating role of depression between fatigue and sleep quality in patients after renal transplantation.

Methods: The general information questionnaire, Pittsburgh Sleep Quality Index (PSQI), Multidimensional Fatigue Inventory (MFI-20) and Patient Health Questionnaire 9 (PHQ-9) were used to evaluate 200 kidney transplant patients in our department from May 2019 to November 2020.

Results: The total PSQI score is (5.31±2.47) points. This study shows that the total score of PSQI is positively correlated with the total score of PHQ and MFI (r=0.422/0.468, P<0.01 for both). Depression partially mediates the relationship between fatigue and sleep quality in kidney transplant patients. The indirect effect is 0.130, accounting for 29.8% of the total effect.

Conclusion: Fatigue may not only directly affect the sleep quality of patients after renal transplantation, but also indirectly affect sleep quality through the mediating effect of depression.

kidney transplantation

Post-operation

Sleep quality

Depression

Sleep disorders are more common in patients with chronic kidney disease (CKD) than in the general population. Research shows that the incidence of various sleep disorders in this population is as high as 80%, such as insomnia, daytime sleepiness and restless legs syndrome, and frequent waking at night,nightmares and so all(1). There are many reasons for sleep disorders in CKD patients, including uremia, anemia and malnutrition(2). It is thought that these factors can be resolved after successful kidney transplantation, and therefore sleep quality may improve after kidney transplantation(3). However, some studies suggest that sleep disorders are not always correctable with a kidney transplant(4). Sleep disturbance in renal transplant patients is closely related to the side effects of multiple immunosuppressants, surgical stress, reduced postoperative physical activity, increased fluid intake, or nocturia(5). Studies have shown that fatigue and negative emotions (such as depression) are important factors in sleep disturbance in kidney transplant patients(6). However, the relationship between the three is unclear. Therefore, this study used a cross-sectional survey method to understand the sleep status of patients after kidney transplantation and analyze the correlation between patients and sleep status. The relationship between fatigue, depression and sleep quality in kidney transplant patients and whether depression mediates the relationship between fatigue and sleep quality. The research results will provide a reference for medical staff to take targeted actions.

1.1 Objects and subjects

This study adopted a simple sampling method and selected 200 patients after kidney transplantation in the outpatient clinic of a tertiary general hospital in Jinan City from November 2019 to May 2020 as the research objects. Patient inclusion criteria: More than 1 year has passed since kidney transplantation; Over 18 years old;Have normal cognitive function, give informed consent and voluntarily participate in this study. Exclusion criteria: Patients with mental illness or disorder of consciousness; Patients with kidney transplantation combined with severe heart, liver and other major organ failure. A total of 200 questionnaires were distributed in this study, 185 questionnaires were recovered, 18 invalid questionnaires were eliminated (when there were conventional answers and many missing items), and 167 valid questionnaires were obtained. This study was approved by the local medical ethics committee.

1.2 Methods

1.2.1 Assessment tools

(1) General information questionnaire was compiled by the researcher, including gender, age, education level, place of residence, marital status, working status, family per capita monthly income, source of kidney transplant, creatinine.

(2) Pittsburgh Sleep Quality Index (PSQI) was compiled by Buysse et al.(7) in 1989, which has good reliability and validity. The PSQI includes a total of 23 items, using a scoring system of 0 to 3 points, with a total score ranging from 0 to 21 points. The higher the total score, the worse the sleep quality and the better the reliability and validity(8). In this study, a PSQI score 7 indicated that the individual had a sleep disorder(8).

(3)Patient Health Questionnaire-9(PHQ-9)

PHQ-9 is a self-rating depression questionnaire, which is mainly used to assess the depressive mood of research subjects in the past 2 weeks. The scale uses a 4-point scoring method from 0 to 3. The higher the score, the more severe the depression. PHQ-9 has good reliability and validity and can be used as a screening tool for depressive symptoms (PHQ-9 ≥ 10)(9). Cronbach’s alpha coefficient in this study was 0.85.

(4)The multi-dimensional fatigue inventory(MFI-20): MFI-20 includes a total of 20 items, including four dimensions: physical fatigue, mental fatigue, decreased motivation, and reduced activity. Each item is rated on a Likert-5 scale. The higher the score, the greater the level of fatigue. It has good reliability and validity(10).

1.2 Statistical analysis

This study used Excel for data entry by two people, and SPSS22.0 for data sorting and analysis. Statistical descriptions used frequency, percentage, mean ± standard deviation (SD ± M). Pearson product-difference correlation analysis was used for correlation. In the mediation effect analysis, the Process plug-in was used to test the mediating effect of depression. The bias correction method proposed by Hayes further verified the mediating effect of depression. P < 0.05 indicates that the difference is statistically significant.

2.1 General information about the study subjects.

General demographic characteristics are shown in Table 1.

Table 1

Demographic and disease-related information of patients after renal transplantation(n, %)
Virable	n	%	Virable	n	%
Gender			Marriage
Male	117	70	Married	147	88.0
Female	50	30	Single	20	12.0
Age			Working status
<45	96	57.5	Working and students	62	37.1
45ཞ60	58	34.7	Retired and unemployed	105	62.9
>60	13	13.8	Family income (monthly,RMB).
Residence			< 2000	54	32.3
City	94	56.3	2000–4000	74	44.3
Rural	73	43.7	> 4000	39	23.4
Education			Is creatinine normal?
Elementary school and below	24	14.4	Yes	75	44.69
Junior high school (technical secondary school)	59	35.3	No	92	55.1
High school	38	22.8	Source of kidney transplant
Bachelor’s degree (junior college) and above.	46	27.5	living body corpse	59 108	35.3 64.7

2.2 Sleep quality scores of patients after kidney transplantation.

The results of this study showed that the PQSI score of patients after kidney transplantation was (5.31 ± 2.47) points, and there was mild to moderate sleep disorder. Comparing the total PQSI score with the domestic norm [15], the score is lower than the domestic norm, and the difference is statistically significant (P < 0.01). The information of each dimension is shown in Table 2.

Table 2

Comparison of sleep quality in patients after kidney transplantation with domestic norms(Mean ± SD)
Item	Mean ± SD		t	P
Item	kidney transplant patients	Norm
PSQI total score	5.31 ± 2.47	6.09±3.90	-4.1	< 0.01^**
Sleep quality	0.91 ± 0.62	1.13±0.72	-4.59	< 0.01^**
Bedtime	1.33 ± 0.80	1.22±0.96	1.76	0.08
Sleeping time	0.26 ± 0.57	0.68±0.96	-9.40	< 0.01^**
Sleep efficiency	0.59 ± 0.86	0.81±1.08	-3.39	< 0.01^**
Sleep disorder	1.48 ± 0.55	1.09±0.47	9.19	< 0.01^**
Hypnotic drugs	0.20 ± 0.57	0.13±0.58	1.53	0.13
Daytime dysfunction	0.54 ± 0.56	1.04±0.99	-11.63	< 0.01^**

2.3 Correlation between sleep quality, fatigue, depression and various dimensions in patients after kidney transplantation.

Pearson correlation analysis results showed that the total PSQI score of patients after kidney transplantation was significantly positively correlated with the total PHQ score and the total MFI score (r = 0.422/0.468, p < 0.01). See Table 3 and Table 4 for details.

Table 3

Correlation between various dimensions of sleep quality and depression in patients after kidney transplantation.
Item	PSQI total score
PSQI total score	0.422^**
Sleep quality	0.228^**
Bedtime	0.207^**
Sleeping time	0.083
Sleep efficiency	0.222^**
Sleep disorder	0.244^**
Hypnotic drugs	0.243^**
Daytime dysfunction	0.407^**
Note: ^** P < 0.01, ^* P < 0.05

Table 4

Correlation between various dimensions of sleep quality and various dimensions of fatigue in patients after kidney transplantation.
Item	MFI total score	Physical fatigue	Mental fatigue.	Power loss	Decreased activity
PSQI total score	0.468^**	0.467^**	0.345^**	0.175^*	0.207^**
Sleep quality	0.227^**	0.268^**	0.126	0.093	0.045
Bedtime	0.335^**	0.340^**	0.171^*	0.150	0.205^**
Sleeping time	0.142	0.145	0.066	0.038	0.115
Sleep efficiency	0.303^**	0.330^**	.187^*	0.132	0.096
Sleep disorder	0.285^**	0.296^**	0.233^**	0.086	0.087
Hypnotic drugs	0.074	-0.001	0.184^*	0.013	0.064
Daytime dysfunction	0.379^**	0.343^**	0.371^**	0.118	0.157^*
Note: ^** P < 0.01, ^* P < 0.05

2.4 Test the mediating effect of depression on fatigue and sleep quality.

Model 4 in the PROCESS program was used to test the mediating effect of depression, with sleep quality as the dependent variable, fatigue as the independent variable, and depression as the mediating variable. In order to further verify the mediating effect of depression, the biased non-parametric percentile method bootstrap method was used. The sample size is set to 5000 and the confidence interval is 95%. As a result, the direct impact of the independent variable fatigue on the dependent variable sleep quality was 0.308 (95% CI [0.137–0.478], P<0.001), and the indirect impact of depression was 0.130, which was 29.8% less than the total impact (see Table 4 and Fig. 1 for details) .The Bootsstrp method was further verified, and the test results showed that the 95% confidence interval of the mediation effect was [0.032 ~ 0.263], which did not exceed 0. The created mediation model showed that depression plays a partial mediating role in fatigue and sleep quality in kidney transplant patients. See Table 5.

Table 5

Test of the mediating effect of depression between fatigue and sleep quality.
Independent variable.	Dependent variable	R²	F	Standardization β	Se	T	P	95%ci
Fatigue	Sleep quality	0.276	12.255	0.438	0.068	6.406	0.000	0.303–0.573
	Depression			0.633	0.062	10.164	0.000	0.510–0.756
	Sleep quality	0.301	11.495	0.308	0.086	3.562	0.000	0.137–0.478
Depression		0.301	11.495	0.206	0.085	2.419	0.000	0.038–0.374
Note: The above data are the results after controlling for demographic variables.

Table 5

Bootstrap method to test the mediating effect of depression.
Mediation model.	Indirect effect size.	Boot standard error.	Boot 95%ci	Relative effect size.
Fatigue-depression-sleep quality.	0.134	0.059	0.032–0.263	29.8%

3.1 Sleep quality of patients after renal transplantation.

The study results showed that the PQSI score of patients after kidney transplantation was (5.31 ± 2.47), indicating the existence of mild to moderate sleep disorder, indicating that patients after kidney transplantation still have sleep disorder problems. Secondly, the PQSI score of patients after kidney transplantation is lower than domestic standards(11). The reason may be that the kidney transplant patients included in this study were transplanted for one year or more. As kidney function returned, her sleep improved. Previous studies have shown that a significant decrease in patients’sleep quality scores was observed at 6-month follow-up after kidney transplantation, and a significant decrease in patients’ sleep quality scores was observed at 6-month follow-up after kidney transplantation(2).. Another study reported that kidney transplantation had no effect on sleep quality during one year of follow-up(12). Therefore, the developmental trajectory of sleep quality in patients after renal transplantation requires further study.

3.2 Correlation between sleep quality, depression and fatigue in patients after renal transplantation.

The results of this study show that there is a significant positive correlation between the total PSQI score and the total PHQ score of patients after kidney transplantation (r = 0.422, P<0.01). In other words, the worse your depression is, the worse your sleep quality will be. Depression is a significant mood change manifested by symptoms such as weight loss, decreased energy levels, and reduced physical activity(13). Among kidney transplant patients, 18–22% develop depressive symptoms after surgery(14). These depressive symptoms are important markers of frailty and are independently associated with adverse outcomes after kidney transplantation, including poor medication compliance, recovery from dialysis treatment, graft failure, cardiovascular mortality, and all-cause mortality(15).Therefore, during the patient’s emotional and psychological fluctuations, the patient’s sleep quality is greatly affected. Correlation analysis showed that sleep quality was significantly positively correlated with fatigue. Our results are consistent with those of Rodrigue et al(16). In other words, the more tired the patient is, the worse the sleep quality is. Symptoms associated with fatigue include inflammation, depressive symptoms, sleep problems, and obesity. Fatigue can lead to severe renal damage, which is common in renal transplant patients with poor compliance with immunosuppressive therapy and is associated with severe deterioration in quality of life(17). Previous studies have also suggested that fatigue severity is closely related to sleep quality disorders, which significantly affects patients’sleep quality(18).

3.3 The mediating role of depression between fatigue and sleep quality.

The results of this study indicate that fatigue not only directly affects the sleep quality of patients after kidney transplantation, but also indirectly affects the sleep quality of patients through the mediating effect of depression. Depression is closely related to fatigue and sleep quality. Previous research has shown that symptoms of depression include sleep disturbances. However, as research continues, it has been discovered that there is a bidirectional relationship between depression and sleep disorders(19).

This study also confirms that there may be bidirectional effects between depression and sleep quality. The study by Gebaba et al.(20)pointed out that almost 80% of patients with depression are accompanied by varying degrees of sleep disorders. Sleep disorder patients with disrupted sleep rhythms are more likely to develop depression than patients with normal sleep. Fatigue is a complex, multifaceted phenomenon determined by physical, psychological, and emotional factors(21). Fatigue can also be described as a condition that causes pain or decreased physical function, resulting in a loss of energy(17).

Many patients continue to experience symptoms of fatigue and weakness after a kidney transplant. Therefore, physical and mental fatigue can affect patients’ mood swings, leading to anxiety and depression. The results of this study will encourage medical staff to not only promote patients’ physical health in daily care, but also consider patients’mental health and promptly identify patients’ negative emotions. We also need to provide patients with effective mental health maintenance and improve sleep and quality of life.

In summary, both fatigue and depression can affect patients’ sleep quality, and depression is a mediating variable between fatigue and sleep quality. When treating sleep disorders in kidney transplant patients, attention should be paid to whether the patients have depressive symptoms, and timely improvement of fatigue in patients with depressive symptoms will help improve the patient’s sleep effect.

Additionally, future studies of sleep status in renal transplant patients should include multicenter longitudinal studies of living and cadaveric transplant patients to extend follow-up and serve as time points to examine trajectories of change. Variables such as anxiety and coping styles also influence the relationship between fatigue and sleep quality. It is recommended to add these variables in the future to further study the mechanisms of action between variables and to gain a detailed understanding of the biopsychosocial factors involved in the occurrence and maintenance of insomnia.

Ethics approval and consent to participate

This study was approved by the Scientific Research Ethics Committee of the Second Hospital of Shandong University(No. KYLL-2023LW023), and relevant survey procedures were in line with the requirements of the Declaration of Helsinki. Written informed consent for participation in this study was provided by the participants.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Funding

Not application

Author Contribution

Jing-Hua Yang,Ping Zhang, wrote the main manuscript text and Zhen Du, Tian Tian, Wei Zhou, Rong-Mei Zhang prepared figures 1-3. All authors reviewed the manuscript.

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No competing interests reported.

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The mediating role of depression in the relationship between fatigue and sleep quality in kidney transplant patients

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Abstract

Figures

Introduction

Objects and methods.

1.2 Methods

1.2.1 Assessment tools

1.2 Statistical analysis

Results

Discussion

Conclusions

Declarations

Ethics approval and consent to participate

Funding

Author Contribution

References

Additional Declarations

Status:

Version 1