Polysomnographic measures of nocturnal sleep in patients on chronic, intermittent daytime haemodialysis vs those with chronic kidney disease.

BACKGROUND

Numerous factors probably contribute to the high prevalence of sleep problems in haemodialysis (HD) patients including metabolic changes and treatment-related factors. In contrast, the sleep problems of patients with chronic kidney disease (CKD) may be more related to psychological factors rather than the metabolic changes associated with renal disease. Thus, the objective of this study was to compare polysomnographic measures of nocturnal sleep in a group of stable patients on chronic, intermittent daytime HD and an age- and gender-matched, metabolically comparable group with CKD, and evaluate the role that quality of life (including psychological factors) and the effects of treatment may play in sleep outcomes.

METHODS

The sample included 16 patients on HD and eight patients with CKD all of whom were free from other significant physical and psychological morbidity. To assess for psychological, functional, family and economic responses to the disease and treatment, all subjects took the Ferrans and Powers Quality of Life Index. HD subjects received treatment three times a week and were adequately dialysed [Kt/V >1.2, equivalent to a weekly glomerular filtration rate (GFR) of 10-15 ml/min]; CKD subjects had an estimated GFR of 14.5 (+/-7.2; range 5.4-28.8) ml/min. All subjects underwent one night of laboratory-based polysomnography. Appropriate statistical procedures were used to explore group differences in sleep variables and their relationship to quality of life dimensions and the effect of treatment.

RESULTS

The CKD patients reported significantly poorer functional and psychological quality of life; both groups had reduced total sleep time and sleep efficiency in comparison with normative data. However, HD subjects had less rapid eye movement sleep (P = 0.032). They also had a higher brief arousal index (P = 0.000), an independent predictor of which was treatment with HD, and respiratory disturbance index (P = 0.061). Less total sleep time, increased wake after sleep onset, lower sleep efficiency, higher periodic limb movement index, and longer latencies to sleep onset and rapid eye movement sleep were also noted in the HD group. Quality of life scores did not predict sleep variables in this small sample.

CONCLUSIONS

The results suggest that the sleep problems of patients with CKD and those receiving chronic, intermittent daytime HD may have different aetiologies; functional and psychological factors may play a more prominent role in the former group, while intrinsic sleep disruption (arousals, apnoeas and limb movements) secondary to the effects of chronic, intermittent daytime HD may play a more significant role in the latter. The findings suggest that further exploration is warranted and that population-specific sleep-promoting interventions may be indicated.