Surveillance of CKD epidemiology in the US - a joint analysis of NHANES and KEEP.

Chronic Kidney Disease (CKD), is highly prevalent in the United States. Epidemiological systems for surveillance of CKD rely on data that are based solely on the NHANES survey, which does not include many patients with the most severe and less frequent forms of CKD. We investigated the feasibility of estimating CKD prevalence from the large-scale community disease detection Kidney Early Evaluation and Program (KEEP, n = 127,149). We adopted methodologies from the field of web surveys to address the self-selection bias inherent in KEEP. Primary outcomes studied were CKD Stage 3-5 (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m2, and CKD Stage 4-5 (eGFR <30 mL/min/1.73 m2). The unweighted prevalence of Stage 4-5 CKD was higher in KEEP (1.00%, 95%CI: 0.94-1.05%) than in NHANES (0.51%, 95% CI: 0.43-0.59%). Application of a selection model that used  variables related to demographics, recruitment and socio-economic factors resulted in estimates similar to NHANES (0.55%, 95% CI: 0.50-0.60%). Weighted prevalence of Stages 3-5 CKD in KEEP was 6.45% (95% CI: 5.70-7.28%) compared to 6.73% (95% CI: 6.30-7.19%) for NHANES. Application of methodologies that address the self-selection bias in the KEEP program may allow the use of this large, geographically diverse dataset for CKD surveillance.

Sleep disorders in end-stage renal disease: 'Markers of inadequate dialysis'?

Excessive daytime sleepiness and sleep disorders, including sleep apnea syndrome, restless legs syndrome, and periodic limb movement disorder, occur with increased frequency in patients with end-stage renal disease (ESRD). The detection and management of sleep disorders in ESRD patients is often challenging but may have significant clinical benefits. Some of the poor quality of life in ESRD may be attributed to the presence of concomitant sleep disorders, yet the classical symptoms of sleep disorders (poor concentration, daytime sleepiness, and insomnia) are often ascribed to the uremic syndrome itself. Conventional risk factors and screening tools used in the diagnosis of sleep disorders seem to have limited applicability in dialysis patients implicating the unique pathophysiology of sleep disorders in ESRD. Emerging evidence suggests that sleep apnea may contribute to the augmented cardiovascular event rates and to the accelerated development of atherosclerosis in ESRD. Whether treatment of sleep disorders in ESRD patients can affect the high morbidity and mortality of ESRD patients has yet to be elucidated. To date, conventional renal replacement therapies do not appear to have a significant impact on the treatment of sleep disorders in ESRD. The promising therapeutic effects of optimal uremia control in the forms of nocturnal hemodialysis and renal transplantation on sleep disorders require further mechanistic and clinical studies.

Sleep quality and clinical correlates in patients on maintenance dialysis.

BACKGROUND: Sleep quality is a subject of increasing interest to clinicians caring for dialysis patients. Self-assessed sleep disturbances have been associated with quality of life outcomes. The goal of this study was to identify clinical and laboratory parameters that are independently associated with overall sleep quality among prevalent dialysis patients. METHODS: The Epworth Sleepiness Scale (ESS) and the Sleep Problems Index (SPI), a questionnaire derived from the Medical Outcomes Study, were administered to 71 dialysis patients and 68 subjects without known kidney disease (control group). The ESS and the SPI sleep item responses between the 2 groups were compared. The sleep items from the SPI were also aggregated into a sleep quality score. Multivariate linear regression analyses of sleep quality scores were used to identify clinical factors that were independently associated with poor sleep. RESULTS: The ESS score was not significantly different between the 2 groups. However, the responses to the SPI sleep items demonstrated significantly impaired subjective sleep quality in dialysis patients compared with control subjects. In addition, overall sleep quality, as measured by the aggregated sleep score, was lower in dialysis patients compared with the control group (41 vs. 47, p < 0.001). In multivariate analyses, factors that were independently associated with poor sleep quality in dialysis patients were male gender (p = 0.006), history of coronary artery disease (p = 0.003), and high phosphate level (p = 0.05). CONCLUSION: This study demonstrates that global sleep quality of dialysis patients is substantially impaired. Poor sleep quality was associated with male gender, coronary artery disease and high serum phosphate level, a modifiable factor. Future studies are needed to examine the relationship of serum phosphate level to sleep quality in dialysis patients.