Association of symptoms of insomnia and sleep parameters among kidney transplant recipients.

OBJECTIVE: Insomnia complaints are frequent among kidney transplant (kTx) recipients and are associated with fatigue, depression, lower quality of life and increased morbidity. However, it is not known if subjective insomnia symptoms are associated with objective parameters of sleep architecture. Thus, we analyze the association between sleep macrostructure and EEG activity versus insomnia symptoms among kTx recipients. METHODS: Participants (n1=100) were selected from prevalent adult transplant recipients (n0=1214) followed at a single institution. Insomnia symptoms were assessed by the Athens Insomnia Scale (AIS) and standard overnight polysomnography was performed. In a subgroup of patients (n2=56) sleep microstructure was also analyzed with power spectral analysis. RESULTS: In univariable analysis AIS score was not associated with sleep macrostructure parameters (sleep latency, total sleep time, slow wave sleep, wake after sleep onset), nor with NREM and REM beta or delta activity in sleep microstructure. In multivariable analysis after controlling for covariables AIS score was independently associated with the proportion of slow wave sleep (ß=0.263; CI: 0.026-0.500) and REM beta activity (ß=0.323; CI=0.041-0.606) (p<0.05 for both associations). CONCLUSIONS: Among kTx recipients the severity of insomnia symptoms is independently associated with higher proportion of slow wave sleep and increased beta activity during REM sleep but not with other parameters sleep architecture. The results suggest a potential compensatory sleep protective mechanism and a sign of REM sleep instability associated with insomnia symptoms among this population.

Association between lunar phase and sleep characteristics.

OBJECTIVES: Popular belief holds that the lunar cycle affects human physiology, behavior, and health, including sleep. To date, only a few and conflicting analyses have been published about the association between lunar phases and sleep. Our aim was to analyze the relationship between lunar phases and sleep characteristics. METHODS: In this retrospective, cross-sectional analysis, data from 319 patients who had been referred for sleep study were included. Individuals with apnea-hypopnea index ≥ 15/h were excluded. Socio-demographic parameters were recorded. All participants underwent one-night standard polysomnography. Associations between lunar cycle (new moon, full moon and alternate moon) and sleep parameters were examined in unadjusted and adjusted models. RESULTS: Fifty-seven percent of patients were males. Mean age for men was 45 ± 14 years and 51 ± 12 years for women. In total, 224 persons had their sleep study done during alternate moon, 47 during full moon, and 48 during new moon. Full moon was associated with lower sleep efficiency [median (%) (IQR): new moon 82 (18), full moon 74 (19), alternate moon 82 (15); P < 0.001], less deep sleep [median (%) (IQR): new moon 9 (9), full moon 6 (4), alternate moon 11 (9); P < 0.001], and increased REM latency [median (min) (IQR): new moon 98 (74), full moon 137 (152), alternate moon 97 (76); P < 0.001], even after adjustment for several covariables. CONCLUSION: The results are consistent with a recent report and the widely held belief that sleep characteristics may be associated with the full moon.

Violent somnambulism: a parasomnia of young men with stereotyped dream-like experiences.

OBJECTIVE: To characterize a subgroup of arousal parasomnias associated with violent behavior in adults. DESIGN: A pilot study on clinical and polysomnographic data of 13 adult patients seen in a tertiary sleep center for the suspicion of arousal parasomnia associated with violence. RESULTS: Nine young patients (8 males 1 female) had a common pattern of abnormalities: similar 'claustrophobic' dream-like experiences and complex, vehement dream enactments; no REM sleep without atonia on polysomnography. We call this syndrome 'violent somnambulism'. The rest of the patients had alcoholic delirium, partial epilepsy, possible REM sleep behavior disorder and a single sleep walking episode provoked by a sleeping pill. CONCLUSIONS AND HYPOTHESIS: Sleep related violence needs thorough diagnostic evaluation for preventing life-threatening consequences. Violent somnambulism appears to be a distinct NREM sleep-related overlap parasomnia.

Obstructive sleep apnea and heart rate variability in male patients with metabolic syndrome: cross-sectional study.

BACKGROUND: Obstructive sleep apnea (OSA) is often accompanied by the metabolic syndrome. Because both conditions are associated with depressed heart rate variability (HRV) separately, our aim was to study whether co-morbid OSA is associated with more reduced HRV in male patients with the metabolic syndrome. METHODS: In this cross-sectional study, 35 men (age, 57±11 years) with the metabolic syndrome (according to International Diabetes Federation criteria) were included. OSA severity was defined by the apnea-hypopnea index (AHI). HRV was assessed by 24-hr ambulatory electrocardiographic monitoring. Standard deviation of all normal-to-normal RR intervals (SDNN), the high frequency power (HFP), and the ratio of low- to high-frequency power (LF/HF) were measured. RESULTS: There were 14, 6, and 8 cases of severe (AHI ≥30/hr), moderate (15/hr≤AHI <30/hr), and mild (5/hr ≤AHI <15/hr) OSA, respectively. Seven patients had no OSA. Patients with mild-moderate or severe OSA had reduced SDNN and HFP values compared to those without OSA. Increasing OSA severity was associated significantly with lower daytime LF/HF ratio [standardized ß regression coefficient (ß)=-0.362, P=0.043] and higher night/day LF/HF ratio (ß=0.377, P=0.023) after controlling for age, duration of diabetes, and severity of metabolic syndrome. CONCLUSIONS: Co-morbid OSA is associated with decreased overall HRV, parasympathetic loss, and impaired diurnal pattern of sympathovagal balance that may further increase the cardiovascular vulnerability of male patients with the metabolic syndrome. The role of the HRV analysis in the risk assessment of these patients warrants further studies.

Lack of association between objectively assessed sleep disorders and inflammatory markers among kidney transplant recipients.

PURPOSE: In patients on dialysis, the results of studies examining the association between sleep disorders and inflammation are controversial. We assessed the association between inflammatory markers and different sleep disorders in a large sample of kidney transplant recipients. METHODS: Cross-sectional study of 100 randomly selected kidney transplant patients who underwent one-night polysomnography ("sleep disorders evaluation in patients after kidney transplantation study") to diagnose obstructive sleep apnea (OSA) and periodic limb movements in sleep (PLMS). Athens Insomnia Scale (AIS) was utilized to assess the prevalence of insomnia. Sociodemographic information and data about medication, comorbidity and laboratory parameters were collected. Levels of inflammatory markers, such as C-reactive protein, serum albumin, white blood cell count, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), were measured. RESULTS: The mean age was 51 ± 13 years, 43% were women, and the prevalence of diabetes was 19%. We found no significant difference in the levels of inflammatory markers between patients with versus without OSA and PLMS. Apnea-hypopnea index showed a significant association with white blood cell count (ρ = 0.23), and weak (ρ < |0.15|), non-significant correlation with the other inflammatory markers. PLM index showed weak (ρ < |0.15|), non-significant correlation with all markers of inflammation. The serum IL-6 level was significantly higher in patients with insomnia (AIS ≥ 10) than in non-insomniacs [median (IQR): 3.2(2.6-5.1) vs. 1.7(1.2-2.9) ng/l; P = 0.009]. The levels of other inflammatory markers were similar between insomniacs and non-insomniacs. CONCLUSIONS: We did not find any association between the presence of objectively assessed sleep disorders and inflammatory markers in kidney transplant patients.

Periodic limb movements in sleep are associated with stroke and cardiovascular risk factors in patients with renal failure.

Periodic limb movements in sleep (PLMS) is prevalent among dialysed patients and is associated with increased risk of mortality. Our study aimed to determine the prevalence of this disease in a sample of transplanted and waiting-list haemodialysed patients. One hundred transplanted and 50 waiting-list patients underwent polysomnography. Moderate and severe diseases were defined as periodic limb movements in sleep index (PLMSI) higher than 15 and 25 events h(-1), respectively. The 10-year coronary heart disease risk was estimated for all patients using the Framingham Score. Moreover, the 10-year estimated risk of stroke was calculated according to the modified version of the Framingham Stroke Risk Profile. PLMS was present in 27% of the transplanted and 42% of the waiting-list group (P = 0.094); the proportion of severe disease was twice as high in waiting-list versus transplanted patients (32 versus 16%, P = 0.024). Patients with severe disease had a higher 10-year estimated risk of stroke in the transplanted group [10 (7-17) versus 5 (4-10); P = 0.002] and a higher 10-year coronary heart disease risk in both the transplanted [18 (8-22) versus 7 (4-14); P = 0.002], and the waiting-list groups [11 (5-18) versus 4 (1-9); P = 0.032]. In multivariable linear regression models the PLMSI was associated independently with the Framingham cardiovascular and cerebrovascular scores after adjusting for important covariables. Higher PLMSI is an independent predictor of higher cardiovascular and cerebrovascular risk score in patients with chronic kidney disease. Severe PLMS is less frequent in kidney transplant recipients compared to waiting-list dialysis patients.

Socio-demographic characteristics, health behaviour, co-morbidity and accidents in snorers: a population survey.

OBJECTIVE: We assessed the socio-demographic correlates of snoring and also the patterns of health behaviour and co-morbidity associated with different types of snoring in the Hungarian population. We wanted to study whether different types of snoring are associated with high-risk health behaviour, chronic illnesses, daytime consequences of poor sleep, and with frequent accidents compared with non-snoring individuals. METHOD: This is a cross-sectional study. Interviews were carried out in the homes of 12,643 people. This was the largest nationally representative study in Central Europe about health behaviour. In the Athens Insomnia Scale, questions about snoring and sleep behaviour, life-style factors and health behaviour, as well as questions on their history and current medical treatment were included in the questionnaire. RESULTS: Thirty-seven percent of males and 21% of females reported loud snoring with breathing pauses. We found a significant increasing trend for the consumption of alcohol and coffee as well as smoking among non-snorers, habitual snorers and loud snorers, respectively. In an ordinal regression model male gender, the presence of smoking, the presence of three or more co-morbid conditions and alcohol consumption were independent predictors of snoring (OR [95% CI], 1.99 [1.85-2.1], 1.76 [1.60-1.92], 1.45 [1.30-1.62] and 1.22 [1.04-1.43], respectively, P < 0.001) after controlling for multiple socio-demographic and clinical variables. The frequency of accidents was higher in the loud snoring group than among non-snoring individuals (24% vs 17%, P < 0.0001). CONCLUSIONS: Snoring is common in the Hungarian adult population. Snoring, especially loud snoring with breathing pauses, is strongly associated with high-risk health behaviour, higher co-morbidity and a higher frequency of accidents.

Depressive symptoms and mortality in patients after kidney transplantation: a prospective prevalent cohort study.

OBJECTIVE: To analyze in a prospective cohort study if depressive symptoms are an independent predictor of mortality in kidney transplant recipients. METHODS: Data from 840 transplanted patients followed at a single outpatient transplant center were analyzed. Sociodemographic parameters and clinical data were collected at enrollment (between August 2002 and February 2003). Participants completed the Center for Epidemiologic Studies-Depression (CES-D) scale. Depression was defined as CES-D score of > or = 18. Data on 5-year outcomes (death censored graft loss or mortality) were collected. RESULTS: The prevalence of depression was 22%. Mortality was higher (21% versus 13%; p = .004) in patients with versus without depression. In a multivariate Cox proportional hazard model, both the baseline CES-D score (hazard ratio(for each 1-point increase) = 1.02; 95% confidence interval, 1.00-1.04) and the presence of depression at baseline (hazard ratio(presence) = 1.66; 95% confidence interval, 1.12-2.47) were significantly associated with mortality. The baseline CES-D score also significantly predicted death censored graft loss (hazard ratio(for each 1-point increase) = 1.03; 95% confidence interval, 1.01-1.05). CONCLUSION: Depressive symptoms are an independent predictor of mortality in kidney transplanted patients.

Sleep apnea is associated with cardiovascular risk factors among kidney transplant patients.

BACKGROUND AND OBJECTIVES: We assessed the prevalence of obstructive sleep apnea (OSA) and its clinical correlates in a large sample of patients who received a kidney transplant (Tx). We also compared the prevalence of the disorder between dialysis patients who were on the waiting list for a Tx (WL) and Tx patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a cross-sectional study of 100 Tx and 50 WL patients who underwent one-night polysomnography (SLeep disorders Evaluation in Patients after kidney Transplantation [SLEPT] Study). Sociodemographic information and data about medication, comorbidity, and laboratory parameters were collected. RESULTS: The prevalence of mild (apnea-hypopnea index [AHI] > or =5/h and <15/h), moderate (AHI > or =15/h and <30/h), and severe OSA (AHI > or =30/h) was 18, 11, and 14% in the Tx group and 28, 16, and 10% in the WL group, respectively. The AHI was significantly correlated with age (rho = 0.34), body mass index (rho = 0.45), neck circumference (rho = 0.4), abdominal circumference (rho = 0.51), and hemoglobin (rho = 0.24) in the Tx group. The proportion of Tx patients who were treated with three or more antihypertensive drugs was significantly higher in the OSA group (56 versus 31%; P = 0.022). Despite taking significantly more antihypertensive drugs, the average systolic BP was still higher in patients with versus without OSA (147 +/- 21 versus 139 +/- 18 mmHg; P = 0.059). CONCLUSIONS: The prevalence of OSA is similar in Tx and WL patients and it may contribute to presence of hypertension in patients who receive a Tx.

Association between restless legs syndrome and depression in patients with chronic kidney disease.

Restless legs syndrome (RLS) is reportedly associated with depression. This association may be mediated by both sleep-dependent and sleep-independent mechanisms. Here we analyze the association between RLS and depressive symptoms in patients with chronic kidney disease (CKD). We also assessed whether the relationship is independent of insomnia. In a cross-sectional study, socio-demographic parameters, laboratory data, and medical history were collected from 788 kidney transplant patients and 161 dialyzed patients. Insomnia, depression, and the presence of RLS symptoms were assessed with standard questionnaires. Patients with probable RLS had a higher prevalence of depressive symptoms than those without RLS (56% vs. 22% with vs. without RLS, respectively; P<.001). Patients presenting RLS symptoms had higher Athens Insomnia Scale (AIS) scores than patients without RLS [median AIS score (interquartile range): 7 (6) vs. 3 (4) with vs. without RLS, respectively; P<.001]. The AIS score correlated with the CES-D score (Spearman's rho=0.54, P<.001). In multivariate analysis, the presence of RLS symptoms was independently associated with depressive symptoms (OR=3.96, 95% CI 2.21-7.1, P<.001). This relationship remained significant even after including insomnia in the model (OR=2.9, CI 1.55-5.43, P<.001). The presence of RLS symptoms is associated with depression in patients with CKD. This relationship remained significant even after accounting for insomnia. Sleep-independent mechanisms may also contribute to the association between RLS and depression in patients with CKD.

The International Quotidian Dialysis Registry: annual report 2006.

Interest in short daily and nocturnal hemodialysis (HD) regimens continues to grow worldwide. Despite growing optimism that these therapies will afford better patient outcomes over conventional HD, the current literature has not been viewed as sufficiently compelling to affect widespread implementation in most jurisdictions. Before these therapies can gain wider acceptance, larger and more rigorous studies will likely be needed. In June 2004, the Quotidian Dialysis Registry, based at the Lawson Health Research Institute at the University of Western Ontario, Canada, began recruiting patients across North America. By using an Internet-based data entry platform, patients from various centers worldwide will eventually be recruited, and studied prospectively. This paper constitutes the second annual update on patient and center recruitment, patient and treatment characteristics, and future directions for the registry.

Validation of the Kidney Disease Quality of Life-Short Form questionnaire in kidney transplant patients.

OBJECTIVE: The aim of this study was to determine the basic psychometric properties, reliability, and validity of the Kidney Disease Quality of Life-Short Form (KDQOL-SF) questionnaire in kidney transplant patients. METHODS: The reliability and validity of the instrument were determined in 418 kidney transplant patients followed in a single outpatient transplant centre. RESULTS: Internal consistency of all the Medical Outcome Study Short Form 36 (SF-36) domains was very good, and the Cronbach's alpha value was above .70 for all but three of the disease-specific subscales. We found significant, moderate to strong negative correlations between most of the KDQOL-SF domains and the Center for Epidemiologic Studies-Depression (CES-D) scores. Finally, substantial differences in KDQOL-SF scores were seen between groups of transplanted patients who were expected to be clinically different, supporting the discriminant validity of the KDQOL-SF instrument. CONCLUSION: We propose that the KDQOL-SF is a reliable and valid tool and most of its subscales can be used to assess health-related quality of life (HRQOL) in kidney transplant patients and to compare HRQOL between different end stage renal disease (ESRD) patient populations.

Factor structure and reliability of the Hungarian version of the Illness Intrusiveness Scale: invariance across North American and Hungarian dialysis patients.

OBJECTIVES: The objectives of this study were to compare the factor structure and to assess the reliability of the Hungarian version of the Illness Intrusiveness Rating Scale (IIRS), testing internal validity and employing simultaneous confirmatory factor analysis (SCFA) in two large samples of North American versus Hungarian patients with end-stage renal disease (ESRD). METHODS: Translation was conducted according to current recommendations. Following pilot testing, 365 maintenance haemodialysis patients completed the scale. Hungarian data were compared with IIRS data from North American ESRD patients undergoing maintenance hemodialysis to evaluate item bias (Group x Item ANOVA). RESULTS: Confirmatory factor analyses indicated a good fit between the previously hypothesized three-factor model ("relationships and personal development", "intimacy", and "instrumental" life domains) of the original English version and the Hungarian translation. Although statistically significant (P<.05), the effect size for the Groups x Items interaction was not substantial. Internal consistency was very good (Cronbach's alpha=.80) for the total score, and, although somewhat lower than ideal, it was still in the acceptable range for the subscales (.64-.67). These numbers are similar to values reported for the original English version. Test-retest reliability was also acceptable. CONCLUSION: The Hungarian translation of the IIRS has the same three-dimensional factor structure as the original English-language version does. Furthermore, it is sufficiently reliable for research applications. These features satisfy important requirements of cultural equivalence.

Restless legs syndrome, insomnia and quality of life in patients on maintenance dialysis.

BACKGROUND: In a cross-sectional study, we analysed the complex relationship between restless legs syndrome (RLS), insomnia and specific insomnia symptoms and health-related quality of life (QoL) in patients on maintenance dialysis. METHODS: Data were obtained from 333 patients on chronic maintenance dialysis. To assess the prevalence of RLS, we used the RLS Questionnaire (RLSQ). The Athens Insomnia Scale (AIS) was used to assess insomnia and QoL was measured with the Kidney Disease Quality-of-Life Questionnaire. RESULTS: The prevalence of RLS was 14%. The number of comorbid conditions was significantly higher in patients with vs without RLS (median: three vs two; P<0.05). RLS patients were twice as likely to have significant insomnia as patients without RLS (35% vs 16%; P<0.05). Furthermore, RLS was associated with impaired overall sleep quality (median AIS score: 8 vs 4; P<0.01) and poorer QoL. RLS was a significant and independent predictor of several of the QoL domains after statistical adjustment for clinical and socio-demographic covariables. Importantly, this association remained significant even after adjusting for sleep quality. CONCLUSIONS: RLS is associated with poor sleep, increased odds for insomnia and impaired QoL in patients on maintenance dialysis. Based on the present results, we suggest that both sleep-related and sleep-independent factors may confer the effect of RLS on QoL.