Associations between poor sleep quality and different measures of obesity.

OBJECTIVE: Poor sleep may be a risk factor for obesity. Previous studies have mainly investigated the effects of sleep duration on body mass index, but research considering overall sleep quality and other anthropometric measures is scarce. The aim of this study was to examine the association between sleep quality and different measures of obesity (general obesity, abdominal obesity, body composition) in a population-based sample of adults. METHODS: The study included 753 participants aged 35-65 years from the BiDirect Study, conducted in Münster, Germany. Participants completed the Pittsburgh Sleep Quality Index (PSQI) on sleep characteristics. Weight, height, and waist circumference were measured by trained study nurses. Body composition (fat mass and fat-free mass) was assessed using bioelectrical impedance analysis. The cross-sectional relationship between sleep quality and measures of obesity was investigated using logistic regression analysis. RESULTS: Among the participants, 65.3% reported good (PSQI ≤ 5) and 34.7% poor (PSQI > 5) sleep quality. We observed a significant association of poorer sleep quality assessed by the continuous PSQI score with general obesity and high body fat (for both, odds ratio = 1.07, 95% confidence interval = 1.01-1.13), adjusted for socio-demographic and lifestyle factors. Further adjustment for depressive symptoms and somatic comorbidities attenuated the relationship. The observed association was mainly driven by the PSQI components sleep latency, sleep disturbances, and daytime dysfunction. CONCLUSIONS: The present study suggests that poor sleep quality may predict obesity and high body fat mass among adults. However, a causal relationship still has to be confirmed by prospective studies with objective measurements of sleep and obesity.

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.

Evaluation of the malnutrition-inflammation score in kidney transplant recipients.

BACKGROUND: Chronic protein-energy wasting, termed malnutrition-inflammation complex syndrome, is frequent in patients with chronic kidney disease and is associated with anemia, morbidity, and mortality in patients on maintenance dialysis therapy. The Malnutrition-Inflammation Score (MIS) recently has been developed and validated in dialysis patients. STUDY DESIGN: Observational cross-sectional study. SETTING & PARTICIPANTS: 993 prevalent kidney transplant recipients. PREDICTOR: MIS computed from change in body weight, dietary intake, gastrointestinal symptoms, functional capacity, comorbid conditions, decreased fat store/Systemic Global Assessment, signs of muscle wasting/Systemic Global Assessment, body mass index, serum albumin level, and serum transferrin level. OUTCOMES: Markers of inflammation and malnutrition, including serum C-reactive protein, interleukin 6, tumor necrosis factor alpha, serum leptin, prealbumin, body mass index, and abdominal circumference. The relationship was modeled by using structural equation models. RESULTS: Mean age was 51 +/- 13 years, 57% were men, and 21% had diabetes. Median time from transplant was 72 months. MIS significantly correlated with abdominal circumference (r = -0.144), serum C-reactive protein level (r = 0.094), serum interleukin 6 level (r = 0.231), and serum tumor necrosis factor alpha level (r = 0.102; P < 0.01 for all). A structural equation model with 2 latent variables (malnutrition and inflammation factor) showed good fit to the observed data. LIMITATIONS: Single-center study, lack of information about vascular access, presence of nonfunctioning kidney transplant, relatively high refusal rate. CONCLUSIONS: Our results confirm that MIS reflects both energy-protein wasting and inflammation in kidney transplant recipients. This simple instrument appears to be a useful tool to assess the presence of protein-energy wasting in this patient population.

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.

Calcium, phosphate and parathyroid metabolism in kidney transplanted patients.

INTRODUCTION: Impaired kidney function is common in kidney-transplanted patients and complications of chronic kidney disease (CKD), such as mineral and bone disorders (MBD) are also prevalent in this population. Similarly to other stages of CKD, increasing evidence supports the association between MBD and cardiovascular risk after kidney transplantation as well. Still, little is known about the prevalence, clinical correlates of MBD and its management in transplanted patients. In this study, we aimed to examine the characteristics of MBD and its associations with clinical parameters in a large prevalent cohort of patients after kidney transplantation. METHODS: Nine hundred and ninety stable patients followed at a single kidney transplant outpatient clinic were included in the study. Detailed medical history, demographic data and routine laboratory results, including Ca, P and intact PTH were collected. Estimated GFR was calculated using the abbreviated MDRD formula, patients were stratified into three groups based on eGFR. Target levels for Ca, P and iPTH were based on CKD stages according to the NKF-K/DOQI guidelines. Standard statistical procedures, binomial and multinomial regressions were used in the analysis. RESULTS: The mean age was 51 years, 57% were males and 21% were diabetic, with 72 months (median) post-transplantation. Most of the patients were in CKD stage 3. Serum phosphorus showed strong negative correlation with graft function in CKD stages 4-5 (r = -0.633, P < 0.001). Hyperphosphatemia was independently associated with the time spent on dialysis before transplantation, serum iPTH and CKD stages 4-5. iPTH showed negative correlation with eGFR in CKD stages 3-5 (rho = -0.289, P < 0.001) and weak positive correlation with time spent on dialysis prior to transplant (rho = 0.114, P < 0.001). Both hyperparathyroidism (42%) and relative hypoparathyroidism (15%) were frequent. The prescription of P-binders (6%) and vitamin D analogs (33%) was sporadic. CONCLUSION: Disturbances of bone and mineral metabolism after transplantation are prevalent and are strongly correlated with the kidney function, similarly to non-transplanted CKD patients. MBD in this population is not adequately managed.

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.

Restless legs syndrome and mortality in kidney transplant recipients.

BACKGROUND: Previous studies showed an association between the presence of restless legs syndrome (RLS) and mortality in patients on dialysis therapy. An association between RLS and cardiovascular risk also was reported in the general population. However, no prospective study to date assessed the association between the presence of RLS and mortality in kidney transplant recipients. In a prospective cohort study (Transplantation and Quality of Life-Hungary Study), we tested the hypothesis that the presence of RLS predicts mortality in transplant recipients. STUDY DESIGN: Prospective cohort study was performed. SETTINGS & PARTICIPANTS: 804 kidney transplant recipients followed up at a single outpatient transplant center were enrolled in the study. Sociodemographic parameters, laboratory data, and medical history were collected at baseline. Data for 4-year outcomes were collected prospectively from patient charts. PREDICTOR: Presence of RLS assessed using the RLS Questionnaire. OUTCOME & MEASUREMENTS: We defined 3 primary outcomes: mortality with functioning graft, return to dialysis therapy, and the combined outcome of these 2. RESULTS: Mean age was 49 +/- 13 years, estimated glomerular filtration rate was 49 +/- 19 mL/min/1.73 m(2), and median time after transplantation was 54 months. During the 4 years, 97 patients died and 63 patients returned to dialysis therapy. Mortality at 4 years was significantly greater in patients who had RLS at baseline: univariate hazard ratio for the presence of RLS was 2.53 (95% confidence interval, 1.31 to 4.87). In multivariate Cox proportional hazard analysis, the presence of RLS significantly predicted mortality (hazard ratio, 2.02; 95% confidence interval, 1.03 to 3.95) after adjustment for several covariables. LIMITATIONS: The RLS Questionnaire was not validated in transplant recipients. We lacked information for key variables, including HLA mismatch, panel reactive antibodies, cold ischemic time, acute rejection episodes, viral infections, smoking status, and dyslipidemia. CONCLUSIONS: RLS, a potentially treatable disease, is a significant risk factor for mortality in kidney transplant recipients.

High prevalence of patients with a high risk for obstructive sleep apnoea syndrome after kidney transplantation--association with declining renal function.

BACKGROUND: Obstructive sleep apnoea syndrome (OSAS) is much more prevalent in patients on dialysis than in the general population. Our aim was to assess for the first time the prevalence of patients with a high risk for OSAS and its clinical correlates in a large sample of kidney transplanted patients. We also wanted to compare the prevalence of the disorder between waitlisted dialysis patients (WL) and kidney transplanted patients (Tx). METHODS: One thousand sixty-seven kidney transplanted patients were asked to participate in a cross-sectional survey ('TransQoL-HU Study'). Socio-demographic data, history of renal disease, medication, comorbidity and laboratory parameters were collected at enrolment. Patients completed a battery of self-administered questionnaires including the Berlin Sleep Apnoea Questionnaire to assess risk status of OSAS. RESULTS: The final analyses included 841 Tx and 175 WL patients. The prevalence of high risk for OSAS was similar in the transplanted group vs WL patients (27% vs 33%). In multivariate logistic regression analysis male gender, older age, lower educational status, worse kidney function, use of hypnotic drugs and comorbidity were independent predictors for high risk of OSAS in kidney transplanted patients. CONCLUSIONS: High risk for sleep apnoea is highly prevalent in the kidney transplanted population. In addition to the well-known risk factors of OSAS (male gender, obesity, use of hypnotic drugs, comorbidity), impaired kidney function was also independently associated with high risk for OSAS.