Prevalence and correlates of fatigue in chronic kidney disease and end-stage renal disease: are sleep disorders a key to understanding fatigue?

BACKGROUND Fatigue is an important symptom to patients with advanced chronic kidney disease (CKD). The aim of this study is to examine the prevalence and severity of fatigue among non-dialysis-dependent CKD and end-stage renal disease (ESRD) patients, to examine the association of fatigue with subjective and objective sleep quality, and to identify other modifiable factors associated with fatigue. METHODS A cross-sectional survey of 87 non-dialysis-dependent CKD (eGFR ≤45 ml/min/1.73 m(2)) and 86 ESRD patients was done using the Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) and 36-Item Short-Form (SF-36) vitality scale. Higher FACIT-F score denoted less fatigue. Objective sleep was assessed using in-home polysomnography. Predictors of fatigue were determined using a linear regression model. RESULTS The mean FACIT-F score among all participants was 34.5 ± 11.0. Mean scores were similar among CKD and ESRD groups (34.25 ± 11.28 vs. 34.73 ± 10.86; p = 0.73). On univariate analyses, patients with higher levels of fatigue were more likely to have cardiovascular disease, benzodiazepine use, depressive symptoms, and slightly lower hemoglobin and serum albumin levels. There was no significant association between severity of sleep apnea and level of fatigue (Apnea Hypopnea Index 20.1 ± 27.6 vs. 20.3 ± 22.0; p = 0.69). Presence of cardiovascular disease, low serum albumin, depressive symptoms, poor subjective sleep quality, excessive daytime sleepiness and restless legs syndrome were independently associated with greater fatigue in multivariable regression models. The FACIT-F score correlated closely with the SF-36 vitality score (r = 0.81, p < 0.0001). CONCLUSIONS Patients with advanced CKD and ESRD experience profound fatigue. Depressive symptoms, restless legs syndrome, excessive daytime sleepiness, and low albumin levels may provide targets for interventions to improve fatigue in patients with advanced CKD.