|Year : 2014 | Volume
| Issue : 4 | Page : 750-755
|Sleep quality and its correlation with serum c-reactive protein level in hemodialysis patients
Amir Emami Zeydi1, Yadollah Jannati2, Hadi Darvishi Khezri3, Afshin Gholipour Baradari4, Fatemeh Espahbodi5, Mojgan Lesani6, Tahereh Yaghoubi7
1 Department of Nursing, Faculty of Nursing and Midwifery, Mazandaran University of Medical Sciences, Sari, and School of Nursing and Midwifery, Mashhad University of Medical Sciences, Mashhad, Iran
2 Psychiatry and Behavioral Sciences Research Center, Faculty of Nursing and Midwifery, Mazandaran University of Medical Sciences, Sari, Iran
3 Department of Nursing, Islamic Azad University, Sari Branch, Sari, Iran
4 Department of Anesthesiology, Mazandaran University of Medical Sciences, Sari, Iran
5 Department of Nephrology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
6 Fatemeh Zahra Hospital, Mazandaran University of Medical Sciences, Sari, Iran
7 Disaster and Emergency Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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|Date of Web Publication||24-Jun-2014|
| Abstract|| |
Poor sleep quality is a common problem that can potentially predict mortality risk and quality of life in hemodialysis (HD) patients. Also, inflammation is a common feature in HD patients. To determine sleep quality and its correlation with serum C-reactive protein (CRP) level in these patients, we studied 132 chronic HD patients in two university-affiliated teaching hospitals in Sari, Iran during September 2010. Pittsburgh Sleep Quality Index was employed to assess the sleep quality of the patients in addition to CRP, albumin, cholesterol, phosphorus and hemoglobin levels. There were 104 (78.7%) patients who suffered from poor sleep quality. A significant correlation was found between serum CRP level and the patients' sleep quality (P <0.05). There was also a significant correlation between sleep quality and serum phosphorus and albumin levels and body mass index (P <0.05). Furthermore, a significant positive correlation existed between the different components of sleep quality and CRP (P <0.05). We conclude that there is a correlation between decreased sleep quality in HD patients and elevated CRP levels, which may have therapeutic implications.
|How to cite this article:|
Emami Zeydi A, Jannati Y, Darvishi Khezri H, Gholipour Baradari A, Espahbodi F, Lesani M, Yaghoubi T. Sleep quality and its correlation with serum c-reactive protein level in hemodialysis patients. Saudi J Kidney Dis Transpl 2014;25:750-5
|How to cite this URL:|
Emami Zeydi A, Jannati Y, Darvishi Khezri H, Gholipour Baradari A, Espahbodi F, Lesani M, Yaghoubi T. Sleep quality and its correlation with serum c-reactive protein level in hemodialysis patients. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2019 Oct 14];25:750-5. Available from: http://www.sjkdt.org/text.asp?2014/25/4/750/134962
| Introduction|| |
The number of hemodialysis (HD) patients has increasingly grown over the past years and an important problem these patients deal with is poor quality of life. , There is a potential correlation between sleep disorders and higher morbidity and mortality rate and poor quality of life. , The poor sleep quality in the HD patients results in poor quality of life and higher morbidity and mortality rates. ,,,, Studies have demonstrated that 40-80% of HD patients suffer from poor sleep quality. , Sleep disorders are associated with physical, behavioral and psychological problems and lead to problems in mental and social performance as well as in interpersonal interactions. 
Inflammatory processes play an important role in morbidity and mortality in HD patients. ,,,, Elevated C-reactive protein (CRP), an inflammatory marker, is a strong predictor of morbidity and mortality in HD patients. , A few studies have been conducted to investigate the correlation between sleep disorders and inflammation.
The present study aimed to determine the correlation between sleep quality and serum CRP levels in HD patients.
| Patients and Methods|| |
This study was conducted on patients undergoing regular 4-h three times a week HD at two university-affiliated teaching hospitals in Sari, Iran during September 2010. We included patients who were willing to participate in the study with age older than 18 years and at least six months of HD.
On the other hand, patients with severe cardiac and respiratory disease, a medical history of infectious disease one month before the study or on immunosuppressive drugs during the past two months were excluded from the study besides patients who had undergone kidney transplant and resumed HD or were receiving hypnotic drugs.
According to the inclusion criteria, 132 of 170 HD initially screened were selected for the study. After informed consents were signed by the patients, we collected pre-HD blood samples to obtain the levels of serum CRP, phosphorus, albumin, hemoglobin and hematocrit.
To determine sleep quality, the Pittsburgh Sleep Quality Index (PSQI) was used in each patient. PSQI is a self-rating questionnaire, which assesses sleep quality during the previous month, and consists of 19 self-rated questions to assess seven components of sleep quality (subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medications and daytime dys-function). The total score of PSQI ranges from 0 to 21; higher scores indicate poorer sleep quality. A global score of 5 or greater indicates a poor sleeper and that the person suffers from moderate sleep problems in at least three sleep component areas or severe sleep problems in two areas.  In this study, the researchers employed the Persian translation of the PSQI, which has been extensively used by Iranian researchers. 
Other variables such as age, gender, weight, height, diseases leading to end-stage renal failure, marital status, hypnotic drugs, HD shift and duration, smoking and exercise were all checked and recorded by interviewing or reading the patients' files. Patients' body mass index (BMI) was also calculated by dividing body weight (kg) by the square of the height (meter).
Hemoglobin and hematocrit levels were calculated using a cell counter (Coulter) and the CRP levels were measured with a Norway kit (England) and NycoCard set using nephelo-metric methods. Moreover, the albumin, cholesterol and phosphorus levels were measured using a standard kit and photometric method using BT3000.
| Statistical Analysis|| |
The collected data were analyzed using the Statistical pack for social sciences (SPSS) version 16. The central and dispersion indices were used for descriptive analysis; Spear-man's rank correlation coefficient was also employed to evaluate the correlations between continuous variables. A t-test was applied to compare the means of the variables with normal distribution. For variables without normal distribution, the Mann-Whitey test was used. Finally, the differences between the non-continuous variables were evaluated using the chi-square and Fisher's tests. The level of significance was set at P <0.05.
| Results|| |
Among the 132 study patients, 69 patients (52.3%) were male. The mean age of the patients was 59.8 ± 13.3 years, with a mean duration of HD of 37.8 ± 3.86 months. While 76 patients (57.6%) irregularly received hypnotic drugs, 56 patients (42.4%) denied ingestion of such drugs. The mean BMI of the patients was 24.58 ± 5.1 kg/m  ; demographic and medical variables of the patients are presented in [Table 1].
|Table 1: Frequency distribution of demographic and medical characteristics of the study patients.|
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As the results revealed, the global PSQI mean score in the patients was 9.55 ± 4.6, and 104 patients (78.7%) suffered from poor sleep quality (Global PSQI score ≥5). Also, the laboratory results indicated that the mean serum CRP levels in the patients was 15.5 ± 1.24 mg/L. The laboratory results are shown in [Table 2].
Statistical analysis of the data disclosed a significant and direct correlation between serum CRP levels and total sleep quality mean score in the patients (r = 0.76, P = 0.0001). [Figure 1] shows the distribution of these two variables, demonstrating a direct correlation between them.
|Figure 1: Distribution of C-reactive protein (CRP) and Pittsburgh Sleep Quality Index (PSQI) score variables in the study patients.|
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Furthermore, there was a reverse correlation between the patients' global sleep quality score and their serum albumin level, while a significant positive correlation was found between the global sleep quality score of the patients and their serum phosphorus levels and BMIs [Table 3]. Likewise, a significant positive correlation existed between the different aspects of the patients' sleep quality and serum CRP levels [Table 4].
|Table 3: Spearman's rank correlations between the patients' global sleep quality score and some laboratory tests.|
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|Table 4: C-reactive protein (CRP) correlation with components of sleep quality in the study patients.|
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There was no statistically significant correlation between the patients' sleep quality and other demographic characteristics or laboratory tests.
| Discussion|| |
The findings of this study demonstrated that the majority of the participants suffered from poor sleep quality. Studies of Tel et al  and Iliescu et al  showed similar percentages to those in our study. In addition, the present study indicates that there is a significant relationship between high serum CRP levels and poor sleep quality in HD patients. The study by Chiu et al  showed that 79.8% of HD patients suffered from poor sleep quality and that their sleep quality had a relationship with serum CRP and IL-1, as inflammatory markers. Similarly, Jenabi et al found a similar correlation between sleep disorders and serum CRP levels in HD pa-tients.  In contrast, Unruh et al did not find such a correlation in the first year of HD. 
A study conducted on the peritoneal dialysis patients revealed that higher serum CRP and IL-18 levels were associated with poor sleep quality.  In a study conducted by Meier-Ewert et al,  it was found that an increase in the IL-6 level and peripheral blood leukocyte count was related to insomnia in subjects without kidney problems. Elevation of CRP may be the result of increased vascular inflammation due to sleep deprivation-related hypertension.  Another study also revealed that sleep deprivation resulted in a significant increase in the IL-1 and IL-6 levels in healthy people.  Generally, natural hemo-static mechanisms of the body in HD patients change to reach a new level of metabolic interactions, which are specific to these patients. These changes are accompanied by the production of some factors such as acute phase proteins, among which CRP is an important one. These factors aggravate atherosclerosis, protein-related malnutrition and cardiovascular problems and increase mortality in HD patients. ,
In general, patients who complain of poor sleep quality used more healthcare services, took more drugs to induce sleep , and had a lower quality of life and decreased functional performance.  Unruh et al demonstrated that poor sleep quality in HD patients was followed by poor quality of life and higher mortality risk.  Moreover, Iliescu et al  suggested that patients with poor sleep quality suffered from both poor quality of life and depression.
Similar to what Unruh et al  pointed out, the results of our study showed a positive correlation between the higher phosphorus level and the poorer sleep quality in HD patients.
A study by Elder et al conducted on 11,351 HD patients in 308 HD centers in seven countries revealed that not only about half of the participants suffered from poor sleep quality but also that their depression rate was twice that of patients with normal sleep quality. Correspondingly, increased phosphorus level and mortality rate correlated with poor sleep quality in these patients.  In contrast, in a study by Al-Jahdani et al, no correlation between insomnia and phosphorus levels in dialysis patients was found.  In addition, Kutner et al observed no significant correlation of serum phosphate levels in incident HD patients and sleep diffi-culty. 
In our present study, we found a significant inverse correlation between serum albumin levels and sleep quality of the patients, similar to the result of other studies. ,, In addition, in this study, a significant positive correlation was found between the patients' BMI and sleep quality. Similarly, Bjorvatn et al  found that the patients with shorter sleep duration had higher BMI.
Our study, however, had some limitations. First, we only used PSQI as a subjective measurement of sleep quality and comprehensive polysomnography was not performed. Also, we only examined the association between one inflammatory marker (CRP) and sleep quality in HD patients. Further studies are needed to examine the correlation of sleep quality with other inflammatory markers, such as IL-6.
In conclusion, this study highlighted the high prevalence of poor sleep quality among the HD patients. Also, a correlation was observed between poor sleep quality and CRP levels, albumin levels, phosphorus levels and BMI that may have therapeutic implications.
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Hadi Darvishi Khezri
Department of Nursing, Islamic Azad University, Sari Branch, Sari
[Table 1], [Table 2], [Table 3], [Table 4]
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