Association of Sleep Difficulty with Kidney Disease Quality of Life Cognitive Function Score Reported by Patients Who Recently Started Dialysis

Sleep disorders are associated with impaired cognition in the general population, but little attention has been given to the potential association between sleep and cognitive function in the dialysis population. This study investigated reported sleep difficulty and cognitive function scores in a national cohort of patients who initiated maintenance hemodialysis and peritoneal dialysis. The cognitive function scale of the Kidney Disease Quality of Life instrument (KDQOL-CF), which measures aspects of cognitive ability that are important for daily functioning (perceived reaction time, ability to concentrate, and tendency to become confused), was used. The study population included 2286 patients who responded to a questionnaire at baseline in the US Renal Data System Dialysis Morbidity and Mortality Study Wave 2. Reported sleep difficulty was associated in a univariate manner with lower KDQOL-CF score. In a multivariable regression analysis that controlled for age, gender, race, education, diabetic ESRD, cardiovascular comorbidity, smoking, hemoglobin, serum albumin, prescribed sleep medications, dialysis modality, pre-ESRD care, bodily pain, and depressed mood, the association of sleep difficulty with KDQOL-CF score remained significant (P < 0.0001); the association also was significant in a multivariable analysis that was restricted to hemodialysis patients and included adjustment for Kt/V (P = 0.001). Depressed mood and sleep medication prescription predicted a lower KDQOL-CF score, and higher educational level and less bodily pain predicted a higher KDQOL-CF score. Increased understanding of links among sleep difficulty, management of sleep difficulty, and cognitive function could benefit multiple dimensions of dialysis patients' quality of life and daily functioning.