Pittsburgh Sleep Quality Index score predicts all-cause mortality in Chinese dialysis patients

Background The relationship between Pittsburgh Sleep Quality Index (PSQI) score and survival of dialysis patients has not been well studied. The aim of this study was to explore the association between PSQI score and all-cause mortality in dialysis patients. Methods Fifty-one hemodialysis and 58 peritoneal dialysis patients were enrolled in this study. PSQI score > 5 and <= 5 indicated "poor sleepers" and "good sleepers", respectively. The primary outcome was all-cause mortality. Kaplan-Meier survival curve and Cox proportional hazards regression analysis were performed. Results The median PSQI score was 7.0 (4.0-10.0). Sixty-seven (61.5%) patients had poor sleep quality (SQ). Compared with good sleepers, poor sleepers had significantly lower levels of hemoglobin [74.0 (61.0, 85.0) vs. 78.0 (68.0, 97.0), P = 0.03] and serum bicarbonate (18.0 +/- 4.5 vs. 20.0 +/- 3.7, P = 0.022). The follow-up time was 69.1 +/- 29.9 months. By multivariate Cox proportional hazards analysis, PSQI total score was the independent risk factor of all-cause mortality [hazard ratio (HR) 1.20, 95% confidence interval (CI) 1.05-1.36, P = 0.007]. Restricted cubic spline (RCS) analysis showed that 7 was the cutoff value at which the effect of PSQI score on mortality changed. Patients with a PSQI score > 7 had a 2.96-fold increased risk of all-cause mortality (HR 2.96, 95% CI 1.15-7.61, P = 0.025). Conclusions PSQI score can be used as a predictor of all-cause mortality in dialysis patients, and those with PSQI > 7 were associated with increased odds of mortality.