Sleep quality in patients with chronic renal failure: a 3-year longitudinal study

Despite the high prevalence of sleep disorders in patients with kidney disease, no relationship has been demonstrated between sleep quality and the degree of renal function in cross-sectional studies. A prospective trial was, therefore, started in patients with chronic renal failure (CRF) to evaluate whether a link exists between the modifications of these parameters observed during a three-year follow-up period.

Sleep quality was determined by the Pittsburgh Sleep Quality Index (PSQI) at baseline and after two and three years (Time 0, 2 and 3, respectively) in 78 patients with various degrees of CRF in association with the main clinical and biochemical variables.

The baseline PSQI averaged 6.2+/-3.8 (range: 0-21, with higher values indicating worse sleep quality) and was significantly increased at both Time 2 and 3 (8.8+/-3.7 and 10.2+/-3.5, respectively, P<0.0001 vs baseline), whereas creatinine clearance progressively decreased (45+/-24 vs 41+/-26 and 32+/-20ml/min, at time 0, 2 and 3, respectively, P<0.0001), although an independent association with PSQI could not be demonstrated after adjustment for confounding factors (P=0.90, mixed linear model).

Our data suggest that the progression of renal disease is accompanied by a progressive worsening of sleep quality; age is strongly related to both phenomena. PSQI represents an easy tool to use to detect sleep disorders and to more effectively evaluate renal patients; the prevention of sleep disorders by early and appropriate treatments could beneficially influence the course of the disease.