Sleep Behavior Disorders in a Large Cohort of Chinese (Taiwanese) Patients Maintained by Long-Term Hemodialysis
2006; Elsevier BV; Volume: 48; Issue: 2 Linguagem: Inglês
10.1053/j.ajkd.2006.04.079
ISSN1523-6838
AutoresWen-Ching Chen, Paik‐Seong Lim, Wen‐Chieh Wu, Hsien-Chang Chiu, Chih‐Hsuan Chen, Ho-Yen Kuo, Tsung-Wei Tsai, Po-I. Chien, Yue-Jane Su, Yu-Liang Su, Sze-Hung Hung, H.F. Woods,
Tópico(s)Obstructive Sleep Apnea Research
ResumoBackground: Disorders of sleep behavior and sleep-related breathing disorders are common in hemodialysis patients. Most such evidence is based on studies involving small numbers of patients. Methods: We undertook a large multicenter analysis of sleep behavior in more than 700 Taiwanese patients on maintenance hemodialysis therapy for 6 months to 20-plus years by using self-administered questionnaires: the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Berlin Questionnaire for risk for sleep apnea, validated for the general population. Patients also completed a questionnaire to assess symptoms related to restless legs and periodic limb movements (PLMs). Sleep behavior was analyzed in relation to demographic and dialysis-related parameters provided by the participating dialysis centers. Results: Sleep disturbance was very common in this cohort, with problems of insomnia (66.6%) exceeding those related to daytime sleepiness (17.8%). Sleep disturbances were associated with restless legs syndrome (RLS)/PLM and a high risk for sleep apnea, determined by using the Berlin Questionnaire. Older age increased the odds of daytime sleepiness, but not insomnia. Lower dialysis dose (single-pool Kt/V) increased the likelihood of daytime sleepiness and was associated with greater rates for RLS/PLM and risk for sleep apnea. Use of antihypertensive medications (a probable surrogate for more severe hypertension) was associated strongly with high risk for sleep apnea. Smoking was associated with RLS/PLM and risk for sleep apnea, whereas consumption of stimulant beverages (coffee and tea) had contrary effects on RLS/PLM and risk for sleep apnea and were not implicated in measures of insomnia or daytime sleepiness. A greater likelihood of insomnia for greater hemoglobin levels and greater likelihood of daytime sleepiness for patients administered vitamin D analogues were not explained by the available data. Conclusion: Sleep disorders and sleep-related breathing disorders are common in hemodialysis patients. Greater attention in the care of dialysis patients needs to be directed to the diagnosis and management of sleep disorders. Background: Disorders of sleep behavior and sleep-related breathing disorders are common in hemodialysis patients. Most such evidence is based on studies involving small numbers of patients. Methods: We undertook a large multicenter analysis of sleep behavior in more than 700 Taiwanese patients on maintenance hemodialysis therapy for 6 months to 20-plus years by using self-administered questionnaires: the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Berlin Questionnaire for risk for sleep apnea, validated for the general population. Patients also completed a questionnaire to assess symptoms related to restless legs and periodic limb movements (PLMs). Sleep behavior was analyzed in relation to demographic and dialysis-related parameters provided by the participating dialysis centers. Results: Sleep disturbance was very common in this cohort, with problems of insomnia (66.6%) exceeding those related to daytime sleepiness (17.8%). Sleep disturbances were associated with restless legs syndrome (RLS)/PLM and a high risk for sleep apnea, determined by using the Berlin Questionnaire. Older age increased the odds of daytime sleepiness, but not insomnia. Lower dialysis dose (single-pool Kt/V) increased the likelihood of daytime sleepiness and was associated with greater rates for RLS/PLM and risk for sleep apnea. Use of antihypertensive medications (a probable surrogate for more severe hypertension) was associated strongly with high risk for sleep apnea. Smoking was associated with RLS/PLM and risk for sleep apnea, whereas consumption of stimulant beverages (coffee and tea) had contrary effects on RLS/PLM and risk for sleep apnea and were not implicated in measures of insomnia or daytime sleepiness. A greater likelihood of insomnia for greater hemoglobin levels and greater likelihood of daytime sleepiness for patients administered vitamin D analogues were not explained by the available data. Conclusion: Sleep disorders and sleep-related breathing disorders are common in hemodialysis patients. Greater attention in the care of dialysis patients needs to be directed to the diagnosis and management of sleep disorders. Editorial, p. 332 Editorial, p. 332 SLEEP DISORDERS (dyssomnias) are common in hemodialysis (HD) patients, occurring in up to 80% of patients,1Wendland K.L. Greinert I. Sleep disorders in hemodialysis patients.Rehabilitation. 1989; 28: 74-77PubMed Google Scholar, 2Holley J.L. Nespor S. Rault R. Characterizing sleep disorders in chronic hemodialysis patients.ASAIO Trans. 1991; 37: 456-457Google Scholar, 3Walker S. Fine A. Kryger M.H. Sleep complaints are common in a dialysis unit.Am J Kidney Dis. 1995; 26: 751-756Abstract Full Text PDF PubMed Scopus (275) Google Scholar, 4Parker K.P. Sleep and dialysis A research-based review of the literature.ANNA J. 1997; 24: 626-639PubMed Google Scholar, 5Sabbatini M. Minale B. Crispo A. et al.Insomnia in maintenance haemodialysis patients.Nephrol Dial Transplant. 2002; 17: 852-856Crossref PubMed Scopus (164) Google Scholar and recently were reviewed by Wadhwa and Akhtar.6Wadhwa N.K. Akhtar S. Sleep disorders in dialysis patients.Semin Dial. 1998; 11: 287-297Crossref Google Scholar Despite the numerous reports in the literature, neither the Kidney Dialysis Outcomes Quality Initiative nor the European Best Practice Guidelines for Dialysis specifically refer to management of sleep problems. Commonly reported sleep disturbances include insomnia (difficulty initiating sleep and/or frequent nocturnal waking) and daytime sleepiness. Dyssomnia in HD patients commonly is associated with restless legs syndrome (RLS) and/or periodic limb movement (PLM).7Winkelman J.W. Chertow G.M. Lazarus J.M. Restless leg syndrome in end-stage renal disease.Am J Kidney Dis. 1996; 28: 372-378Abstract Full Text PDF PubMed Scopus (357) Google Scholar Dyssomnia also is associated with sleep-related breathing disorder (sleep apnea [SA]), which is more common in patients with chronic kidney disease and dialysis patients.8Kimmel P.L. Miller G. Mendelson W.B. Sleep apnea syndrome in chronic renal disease.Am J Med. 1989; 86: 308-314Abstract Full Text PDF PubMed Scopus (238) Google Scholar, 9Mendelson W.B. Wadhwa N.K. Greenberg H.E. Gujaverty K. Bergofsky E. Effect of hemodialysis on sleep apnea syndrome in end-stage renal disease.Clin Nephrol. 1990; 33: 247-251PubMed Google Scholar Impairment of health-related quality of life in HD patients is associated with sleep disorders10Iliescu E.A. Opp H. McMurray M.H. et al.Quality of sleep and health-related quality of life in haemodialysis patients.Nephrol Dial Transplant. 2003; 18: 126-132Crossref PubMed Scopus (250) Google Scholar, 11Mucsi I. Molnar M.Z. Rethelyi J. et al.Sleep disorders and illness intrusiveness in patients on chronic dialysis.Nephrol Dial Transplant. 2004; 19: 1815-1822Crossref PubMed Scopus (104) Google Scholar and sleep-related breathing disorders.12Sanner B.M. Tepel M. Esser M. et al.Sleep-related breathing disorders impair quality of life in haemodialysis recipients.Nephrol Dial Transplant. 2002; 17: 1260-1265Crossref PubMed Scopus (58) Google Scholar More worrying is the association of SA or hypopnea with adverse effects on blood pressure control and left ventricular remodeling and the association of SA with risk for cardiovascular events.13Zocalli C. Malamaci F. Tripepi G. Nocturnal hypoxemia predicts incident cardiovascular complications in dialysis patients.J Am Soc Nephrol. 2002; 13: 729-733PubMed Google Scholar In addition, sleep deficit has been related to immune suppression.14Irwin J. Effects of sleep and sleep loss on immunity and cytokines.Brain Behav Immun. 2002; 16: 503-512Crossref PubMed Scopus (283) Google Scholar Thus, sleep disorders possibly are associated with the 2 most common causes of morbidity and mortality in dialysis patients: cardiovascular disease and infection. Causes of sleep disturbance in dialysis patients are unknown and likely to be multifactorial. Dyssomnia and its associations are evident in patients with advanced chronic kidney disease, appear to worsen as chronic kidney disease progresses, and are ameliorated only partially by dialysis treatment.1Wendland K.L. Greinert I. Sleep disorders in hemodialysis patients.Rehabilitation. 1989; 28: 74-77PubMed Google Scholar, 2Holley J.L. Nespor S. Rault R. Characterizing sleep disorders in chronic hemodialysis patients.ASAIO Trans. 1991; 37: 456-457Google Scholar, 3Walker S. Fine A. Kryger M.H. Sleep complaints are common in a dialysis unit.Am J Kidney Dis. 1995; 26: 751-756Abstract Full Text PDF PubMed Scopus (275) Google Scholar Although nocturnal quotidian HD was reported to improve sleep patterns, only modest effects of this intense modality of HD were seen for RLS and PLM, whereas significant improvement was reported for SA.15Hanly P.J. Gabor J.Y. Chan C. Pierratos A. Daytime sleepiness in patients with CRF Impact of nocturnal hemodialysis.Am J Kidney Dis. 2003; 41: 403-410Abstract Full Text PDF PubMed Scopus (129) Google Scholar We are aware of only 1 other large cohort observational study that assessed self-reported sleep disturbances in HD patients.5Sabbatini M. Minale B. Crispo A. et al.Insomnia in maintenance haemodialysis patients.Nephrol Dial Transplant. 2002; 17: 852-856Crossref PubMed Scopus (164) Google Scholar In that study, the investigators devised their own instrument for assessing sleep disorders, whereas we choose to use assessment instruments validated in the general population. Complete analysis of sleep disorders that might direct specific therapy are complex and time consuming (eg, polysomnography in sleep laboratories). To identify patients who might benefit most from such studies, it is first required to undertake screening studies with validated instruments. We have undertaken such a cohort study in more than 700 HD patients treated in 10 dialysis centers affiliated with Nephrocare Asia Pacific, Taiwan (a business unit of Fresenius Medical Care). Our findings generally support those of smaller studies and additionally provide possible new insights into the understanding of dyssomnias in HD patients. The study was conducted between September 1, 2004, and December 31, 2004. Of the 12 Nephrocare centers then operating in Taiwan, 10 centers agreed to recruit study subjects. A total of 1,024 patients were approached to participate in a self-assessment of sleep health, and 806 patients (78.7%) agreed. Of these, 736 patients completed the provided self-assessment questionnaires. The centers provided additional demographic data and data related to dialysis and laboratory parameters for each patient. The study was approved by the Medical Advisory Committee of Nephrocare Asia Pacific, Taiwan, following good practice guidelines for the conduct of clinical studies. Three validated questionnaires (translated into Chinese) were self-administered by the patients, assisted as required by dialysis center staff: the Pittsburgh Sleep Quality Index (PSQI),16Buysse D.J. Reynolds C.F. Monk T.H. Berman S.R. Kupfer D.J. The Pittsburgh Sleep Quality Index A new instrument for psychiatric practice and research.Psychiatry Res. 1989; 28: 191-213Abstract Full Text PDF Scopus (19307) Google Scholar the Epworth Sleepiness Score (ESS),17Johns M.W. A new method for measuring daytime sleepiness The Epworth Sleepiness Scale.Sleep. 1991; 14: 540-545Abstract Full Text Full Text PDF PubMed Scopus (61) Google Scholar and the Berlin Questionnaire18Netzer N.C. Stoohs R.A. Netzer C.M. et al.Using the Berlin Questionnaire to identify patients at risk for sleep apnea syndrome.Ann Intern Med. 1999; 131: 485-491Crossref PubMed Scopus (2104) Google Scholar for identification of risk for SA. Although not specifically validated for a Chinese-speaking population, we found no components of the questionnaires that might make them inapplicable for this population. In addition, patients completed a questionnaire with their physicians to assess the presence of RLS and PLM of sleep. Patients documented their consumption of alcohol, coffee, and tea and their use of hypnotic agents. Participating dialysis centers provided relevant and coincident data for dialysis prescription (frequency, dialysis time, filter flux, and blood flow rate); use of erythropoietin, vitamin D analogues, and antihypertensive medications; and results of laboratory tests, including calculated single-pool Kt/V (spKt/V). For laboratory results, reliance was placed on the routine monthly blood testing of patients according to procedures in place in each center. All data initially were entered in an Excel database (Microscoft Corp, Seattle, WA) and subsequently uploaded to an SPSS data file (SPSS, version 13; SSPS Inc, Chicago, IL) for analysis. As appropriate, data are summarized as mean ± SD or median and range or interquartile range. Significance for associations was tested by using Spearman correlation and Kruskal-Wallis tests, as appropriate. To assess the possible influence of demographic and other variables on measures of sleep health, univariate logistic regression models were established for the odds of PSQI score higher than 5 (insomnia) or ESS score higher than 10 (daytime sleepiness), risk for SA (Berlin Questionnaire: high risk, 1; no risk, 0), and reporting of RLS/PLM (yes/no). For logistic regression analyses, variables were entered by using the forward conditional method, with statistical significance determined for α = 0.05. Of 736 completed questionnaires, 26 were rejected for incompleteness of data. Principal demographic and clinical characteristics of respondents are listed in Table 1. Mean age was 57.7 ± 13.4 (SD) years, and median time on dialysis therapy was 58 months (range, 6 to 287 months). Twenty-four percent of patients had diabetes. Ninety percent were administered erythropoietin; 38%, antihypertensive medications; and 25%, vitamin D analogues. Alcohol consumption was extremely low (<2% of patients), and less than 10% of patients smoked cigarettes (20% in males). Less than 5% regularly drank coffee, whereas 19% regularly consumed tea. More than 35% of patients stated that they regularly used hypnotics to aid sleep. Fifteen percent of patients dialyzed in the evening, and the remainder were divided equally between morning and afternoon shifts. All patients dialyzed against bicarbonate-buffered dialysate and with dialysis machines with volumetrically controlled ultrafiltration. Thirty-eight percent of patients regularly dialyzed with a high-flux membrane. Average dialysis session duration was 4 hours, with little spread. Average blood flow rate was 269 ± 35 mL/min, and average achieved spKt/V was 1.47 ± 0.29: women had a higher spKt/V than men (1.56 ± 0.29 versus 1.37 ± 0.25; P < 0.0001). Patients generally were well nourished (serum albumin, 3.9 ± 0.4 g/dL), and mean values for calcium, phosphate, calcium-phosphate product, and intact parathyroid hormone (iPTH) were within acceptable ranges (Table 1).Table 1General CharacteristicsWomen375 (52.8)Men335 (47.2)Diabetes167 (23.5)Age (y)57.6 ± 13.38Vintage (mo)58 (6–287)Antihypertensives266 (37.5)Erythropoietin639 (90.0)Vitamin D analogues176 (24.8)Drink alcohol13 (1.8)Smoke cigarettes70 (9.9)Drink coffee29 (4.1)Drink tea134 (18.9)Drink coffee or tea153 (21.5)Require hypnotics for sleep252 (35.5)Dialysis Morning307 (43.2) Afternoon296 (41.7) Evening107 (15.1)Dialyzer High flux271 (38.2) Low flux439 (61.8)Blood flow (mL/min)269 ± 35Dialysis time (h)4.01 ± 0.23Predialysis blood urea nitrogen (mg/dL)61.7 ± 16.21spKt/V1.47 ± 0.29Hemoglobin (g/dL)10.2 ± 1.44Albumin (g/dL)3.91 ± 0.40Creatinine (mg/dL)12.0 ± 4.18Sodium (mEq/L)138.8 ± 3.42Potassium (mEq/L)4.53 ± 0.77Chloride (mEq/L)100. ± 4.26Calcium (mg/dL)9.64 ± 0.91Phosphate (mg/dL)4.66 ± 1.43Calcium-phosphate product44.8 ± 14.15iPTH (pg/mL)203.5 ± 304.2NOTE. To convert blood urea nitrogen in mg/dL to mmol/L, multiply by 0.357; hemoglobin and albumin in g/dL to g/L, multiply by 10; creatinine in mg/dL to μmol/L, multiply by 88.4; sodium, potassium, and chloride in mEq/L to mmol/L, multiply by 1; calcium in mg/dL to mmol/L, multiply by 0.2495; phosphates in mg/dL to mmol/L, multiply by 0.323; iPTH in pg/mL to pmol/mL, multiply by 0.9. Open table in a new tab NOTE. To convert blood urea nitrogen in mg/dL to mmol/L, multiply by 0.357; hemoglobin and albumin in g/dL to g/L, multiply by 10; creatinine in mg/dL to μmol/L, multiply by 88.4; sodium, potassium, and chloride in mEq/L to mmol/L, multiply by 1; calcium in mg/dL to mmol/L, multiply by 0.2495; phosphates in mg/dL to mmol/L, multiply by 0.323; iPTH in pg/mL to pmol/mL, multiply by 0.9. Median values and percentile distributions and frequencies for relevant sleep health indices are shown in Table 2 and Fig 1. We were unable to identify a significant impact of patient sex for any of the measured indices (ESS and PSQI) and therefore report these results for men and women together. Values for the PSQI were normally distributed, whereas those for the ESS were highly skewed (Fig 1). Daytime sleepiness (ESS score > 10) was reported by 16.8% of patients, whereas problems with nocturnal sleeping were present in 66.6% of patients. Men and women had similar scores for the PSQI and ESS. RLS and/or PLM were reported by 23% of patients. According to results of the Berlin Questionnaire, 20% of patients were at risk for SA. Men had significantly greater rates for both conditions compared with women (risk for SA, P < 0.0001; RLS/PLM, P = 0.007).Table 2Quality of SleepMinimum25th PercentileMedian75th PercentileMaximumESS025824PSQI047.51120Patients with:AllMenWomen PSQI > 5 (%)66.6265.3767.73 ESS > 10 (%)16.7616.1217.33 RLS (%)12.9614.6311.47 PLM (%)12.9616.1210.13 RLS and/or PLM (%)22.9627.4618.93 High risk for SABerlin Questionnaire.20.1425.9714.93 Berlin Questionnaire. Open table in a new tab Significant associations (Kruskal-Wallis) for RLS/PLM were identified for a high PSQI score (P = 0.04), but not for a high ESS score (P = 0.07). RLS/PLM was associated with a high risk for SA (P = 0.013), lower spKt/V (P = 0.006), smoking (P = 0.038), and consumption of coffee (P = 0.001), but not consumption of tea (P = 0.233). No significant associations for RLS/PLM were identified for age, dialysis vintage, diabetes, use of antihypertensives, or blood hemoglobin, serum albumin, calcium, phosphate, or iPTH levels. For risk for SA, significant associations were seen for use of antihypertensives (P < 0.0001), smoking (P = 0.005), consumption of tea (P = 0.009), but not coffee (P = 0.58), and lower spKt/V (P = 0.003). Risk for SA also was associated with high PSQI (P = 0.003) and high ESS scores (P < 0.0001). No significant associations for risk for SA were identified for age, vintage, diabetes, or blood hemoglobin, serum albumin, calcium, phosphate, or iPTH levels. Body mass index for patients at high risk for SA (22.62 ± 3.95 kg/m2) was not significantly different from that of patients without this risk (22.25 ± 3.56 kg/m2), and only 9 of 144 patients with high Berlin Questionnaire scores had a body mass index greater than 30 kg/m2. Use of hypnotics was associated with RLS/PLM (P = 0.005), but not risk for SA (P = 0.22). Four logistic regression models were calculated for each PSQI score higher than 5, ESS score higher than 10, reported RLS/PLM, and high risk for SA by Berlin Questionnaire. Variables entered in the models included patient sex; age; diabetes; dialysis vintage; type of dialyzer (low or high flux); dialysis shift (morning, afternoon, evening); categorical variables for consumption of tea and coffee; cigarette smoking; use of antihypertensives, vitamin D analogues, and hypnotics; and laboratory variables, including hemoglobin, albumin, creatinine, calcium-phosphate product, iPTH, and calculated spKt/V. For each model, sleep indices other than the dependent variable were included as either scalar (PSQI and ESS) or categorical variables (risk for SA, RLS/PLM). Results of the final iterations for each model are listed in Table 3.Table 3Logistic Regression Models for Sleep DisordersPOdds95% CILowerUpperLogistic regression PSQI > 5 Use hypnotics (yes v no)<0.000115.3568.75426.937 Hemoglobin (g/dL)0.0271.1681.0181.336 ESS (unit) 10 Age (y)0.0091.0261.0061.046 Vintage (mo)0.0090.9940.9890.998 Use hypnotics (yes v no)0.0490.5920.3520.997 Use vitamin D analogue (yes v no)0.0391.6751.0262.735 Risk for SA (yes v no)<0.00013.9152.4706.206 Albumin (g/dL)0.0400.5410.3000.973 PSQI (unit)0.0081.0791.0201.141Logistic regression RLS/PLM Diabetes (yes v no)0.0321.6031.0432.465 Consumes coffee (yes v no)0.0013.7421.6668.404 Low-flux dialyzer (v high flux)0.0330.6600.4500.966 Creatinine (mg/dL)0.0011.0711.0271.117 PSQI (unit)<0.00011.1021.0561.150 ESS (unit)0.0051.0581.0171.100Logistic regression risk for SA Sex (female v male)0.0050.5470.3600.831 Use antihypertensives (yes v no)<0.00012.2201.4793.331 Consumes tea (yes v no)0.0111.8601.1503.006 PSQI (unit)0.0291.0541.0051.104 ESS (unit) 5) than daytime somnolence (ESS score > 10), although both indices of dyssomnia correlated. Men and women scored equally on the PSQI and ESS, but men were more likely to be at risk for SA. The likelihood of daytime sleepiness, but not insomnia, was associated with older age. We could not identify an additional risk for sleep disturbance comparing patients with and without diabetes, which is consistent with the Italian study,5Sabbatini M. Minale B. Crispo A. et al.Insomnia in maintenance haemodialysis patients.Nephrol Dial Transplant. 2002; 17: 852-856Crossref PubMed Scopus (164) Google Scholar but diabetes increased the likelihood of RLS/PLM. Current smoking was associated with RLS/PLM and risk for SA (Kruskall Wallis), but was not an independent predictor of either in logistic regression. Consumption of stimulant beverages (coffee and tea) also did not significantly impact on the odds of high PSQI and ESS scores and had contrary effects on RLS/PLM (coffee increased) and risk for SA (tea increased). We probably also should have enquired about other beverages, such as colas. Use of antihypertensive medications was associated strongly with risk for SA. Assuming that use of antihypertensive medications identifies patients with more severe hypertension, this association may be cause and effect. Obstructive SA (the form more likely to be associated with dialysis therapy) is associated with hypertension. Blood pressure increases during and immediately after apneic episodes, and this finding was confirmed in dialysis patients.20Zoccali C. Benedetto F.A. Tripepi G. et al.Nocturnal hypoxemia, night-day arterial pressure changes and left ventricular geometry in dialysis patients.Kidney Int. 1998; 53: 1078-1084Crossref PubMed Scopus (120) Google Scholar This increase in blood pressure reflects a surge of sympathetic activity about the time of apneic episodes, but other and complex cardiodynamic responses are likely. In at least 1 well-controlled study, continuous positive airway pressure decreased nocturnal blood pressure and had a modest effect on daytime blood pressure.21Dimsdale J.E. Loredo J.S. Profant J. Effect of continuous positive pressure airways pressure on blood pressure. A placebo trial.Hypertension. 2000; 35: 144-147Crossref PubMed Scopus (271) Google Scholar In the longer term, SA and the consequent hypoxemia are associated with left ventricular hypertrophy22Zocalli C. Mallamaci F. Tripepi G. Benedetto F.A. Autonomic neuropathy is linked to nocturnal hypoxemia and to concentric hypertrophy and remodelling in dialysis patients.Nephrol Dial Transplant. 2001; 16: 70-77Crossref Scopus (59) Google Scholar and predict adverse cardiovascular outcomes in dialysis patients.13Zocalli C. Malamaci F. Tripepi G. Nocturnal hypoxemia predicts incident cardiovascular complications in dialysis patients.J Am Soc Nephrol. 2002; 13: 729-733PubMed Google Scholar Zocalli et al22Zocalli C. Mallamaci F. Tripepi G. Benedetto F.A. Autonomic neuropathy is linked to nocturnal hypoxemia and to concentric hypertrophy and remodelling in dialysis patients.Nephrol Dial Transplant. 2001; 16: 70-77Crossref Scopus (59) Google Scholar also provided evidence that SA may contribute to autonomic neuropathy in HD patients. Combined, effects of SA on left ventricular remodeling and autonomic neuropathy therefore might contribute to such intradialytic symptoms as hypotension. As far as we are aware, such an association has not been researched. In our population, 20% of patients had a high risk for SA, determined by using the Berlin Questionnaire. These patients are candidates for more detailed sleep studies, including polysomnography and oximetry. Appropriate management of SA possibly would aid in management of hypertension, decrease the risk for cardiovascular disease, and ameliorate intradialytic symptomatic hypotension. Our data also suggest that management of SA would improve daytime sleepiness. Dialysis shift had no independent effect on any of the recorded sleep patterns, whereas Sabbatini et al5Sabbatini M. Minale B. Crispo A. et al.Insomnia in maintenance haemodialysis patients.Nephrol Dial Transplant. 2002; 17: 852-856Crossref PubMed Scopus (164) Google Scholar identified greater odds of insomnia for patients dialyzing in the morning. However, in our patients, risk for SA was significantly less in patients dialyzing on the morning shift (P = 0.031, Mann-Whitney U test) compared with afternoon and evening shifts. This finding may reflect confounding for male patients, who were more likely to dialyze in the evenings. We could not identify an effect of dialyzer membrane flux on dyssomnia. Lower dose of dialysis (spKt/V) was associated with RLS/PLM and risk for SA, but dialysis dose was not an independent predictor of any sleep disorder, and the association of low spKt/V and RLS/PLM and risk for SA may be confounded by male sex (lower spKt/V than women). Somnolence is a recognized symptom of advanced renal failure, and patients report greater alertness after initiation of dialysis therapy. This suggests retention of uremic toxin(s) with soporific properties, but also may reflect a complex derangement of multiple neurotransmitter systems that is only partially amenable to dialysis treatment. Yoshioka et al23Yoshioka M. Ishii T. Fukonishi I. Sleep disturbance of end-stage renal disease.Jpn J Psychiatry Neurol. 1993; 47: 847-851PubMed Google Scholar reported actual worsening of sleep behavior after initiation of dialysis treatment, and the finding that sleep disturbance is similar on dialysis and nondialysis days is not consistent with a dialyzable soporific toxin(s) exerting an acutely reversible effect on sleep behavior.3Walker S. Fine A. Kryger M.H. Sleep complaints are common in a dialysis unit.Am J Kidney Dis. 1995; 26: 751-756Abstract Full Text PDF PubMed Scopus (275) Google Scholar, 24Velga J. Goncalves N. Gomez F. et al.Sleep disturbances in end-stage renal disease patient on hemodialysis.Dial Transplant. 1997; 26: 380-384Google Scholar We are not aware of studies that specifically examined the relationship between dialysis dose or type (diffusive versus convective) and sleep disorders, although as reported, long nocturnal quotidian dialysis may improve some features of disordered sleep.15Hanly P.J. Gabor J.Y. Chan C. Pierratos A. Daytime sleepiness in patients with CRF Impact of nocturnal hemodialysis.Am J Kidney Dis. 2003; 41: 403-410Abstract Full Text PDF PubMed Scopus (129) Google Scholar The increased odds of high PSQI score for greater hemoglobin level and for high ESS score for use of vitamin D analogues were unexpected results for which we cannot speculate about the cause or association and that may simply be spurious findings arising from statistical analysis. Although dyssomnias and sleep-related breathing disorders in dialysis patients are common in the medical literature, the absence of reference to these disorders in the index of available textbooks about dialysis might suggest that sleep disorder is not a cause for concern. We confirm a high prevalence of sleep disorders in this large population of Taiwanese HD patients and believe it is a cause for concern and appropriate management. Lifestyle and dietary habits in this population may differ from those in other cultures and races, so we cannot confidently state that our findings are representative, but they generally are consistent with those of the Italian patients of Sabbatini et al5Sabbatini M. Minale B. Crispo A. et al.Insomnia in maintenance haemodialysis patients.Nephrol Dial Transplant. 2002; 17: 852-856Crossref PubMed Scopus (164) Google Scholar and results of smaller studies. We are especially alarmed at the high prevalence of risk for SA, 10-fold greater than reported in the general adult population,25Young T. Palta M. Dempsey J. Skatrud J. Weber S. Badr S. The occurrence of sleep-disordered breathing among middle-aged adults.N Engl J Med. 1993; 328: 1230-1235Crossref PubMed Scopus (8513) Google Scholar because of its known association with risk for cardiovascular disease and possible contribution to hypertension.13Zocalli C. Malamaci F. Tripepi G. Nocturnal hypoxemia predicts incident cardiovascular complications in dialysis patients.J Am Soc Nephrol. 2002; 13: 729-733PubMed Google Scholar, 20Zoccali C. Benedetto F.A. Tripepi G. et al.Nocturnal hypoxemia, night-day arterial pressure changes and left ventricular geometry in dialysis patients.Kidney Int. 1998; 53: 1078-1084Crossref PubMed Scopus (120) Google Scholar, 22Zocalli C. Mallamaci F. Tripepi G. Benedetto F.A. Autonomic neuropathy is linked to nocturnal hypoxemia and to concentric hypertrophy and remodelling in dialysis patients.Nephrol Dial Transplant. 2001; 16: 70-77Crossref Scopus (59) Google Scholar For those patients, it is planned to pursue further diagnostics and, as appropriate, implement specific treatment. However, other less life-threatening forms of dyssomnia in dialysis patients are likely to impair functioning and quality of life,9Mendelson W.B. Wadhwa N.K. Greenberg H.E. Gujaverty K. Bergofsky E. Effect of hemodialysis on sleep apnea syndrome in end-stage renal disease.Clin Nephrol. 1990; 33: 247-251PubMed Google Scholar, 10Iliescu E.A. Opp H. McMurray M.H. et al.Quality of sleep and health-related quality of life in haemodialysis patients.Nephrol Dial Transplant. 2003; 18: 126-132Crossref PubMed Scopus (250) Google Scholar and remedial measures should be actively pursued. In the absence of specific guidelines, dialysis patients should receive the benefit of sleep hygiene remedial measures effective in the general population.26Stepanski E.J. Wyatt J.K. Use of sleep hygiene in the treatment of insomnia.Sleep Med Rev. 2003; 7: 215-225Abstract Full Text PDF PubMed Scopus (475) Google Scholar As with adequate nutrition, adequate sleep is a necessity of normal living. Unlike the attention given to adequate nutrition in dialysis patients, little or no attention is given to ensuring adequate sleep. This is a deficit that requires redressing. Since submitting this report, we have become aware of another large (883 Italian patients) cohort screening study of sleep disorders in dialysis patients. Their results are very similar to ours in that insomnia was present in 69.1% and daytime sleepiness was present in 11.8% of patients. RLS was reported in 18.4% and high risk for SA was reported in 23.6%. Taken together and from 2 diverse ethnicities, the report from Merlino et al27Merlino G. Piani A. Dolso P. et al.Sleep disorders in patients with end-stage renal disease undergoing dialysis therapy.Nephrol Dial Transplant. 2006; 21: 184-190Crossref PubMed Scopus (251) Google Scholar and our own clearly identify disordered sleep in dialysis patients as a problem requiring more intensive management. Sleep and ESRD: A Wake-Up CallAmerican Journal of Kidney DiseasesVol. 48Issue 2PreviewIN AN EXTENSIVE, well-conducted, and nicely presented study, Chen et al1 report the extraordinarily high prevalence of subjective sleep complaints in a huge sample of hemodialysis (HD) patients. This presents a special and timely opportunity to reflect on the current state of knowledge, therapeutic implications, and future research directions in the arena of sleep complaints, sleep disorders, and chronic renal failure (CRF). Full-Text PDF
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