Cognitive Impairment is Associated with Mortality in Hemodialysis Patients

Background: The prevalence of cognitive impairment in hemodialysis patients is notably high. In previous studies performed in the general population, cognitive impairment has been associated with increased mortality. Objective: We evaluated the relationship between global cognitive function tested by a short screening instrument and mortality in hemodialysis patients. Methods: Cognitive testing was performed in 242 maintenance hemodialysis patients under standardized conditions at baseline using the Montreal Cognitive Assessment (MoCA). Cognitive impairment was defined as a MoCA test score <= 24 points, as published previously. All-cause mortality was monitored during a median follow-up of 3.54 years. Kaplan-Meier plot and Cox regression model adjusted for known risk factors for mortality in hemodialysis patients were used to examine a possible association between global cognitive function and all-cause mortality. Results: A MoCA test score <= 24 points resulted in a significant almost 3-fold higher hazard for all-cause mortality (unadjusted hazard ratio [HR]: 2.812; 95% confidence interval [95% CI]: 1.683-4.698; p <0.001). After adjustment, this association was attenuated but remained significant (adjusted HR: 1.749; 95% CI: 1.007-3.038; p = 0.047). Conclusion: Impairment of global cognitive function measured by a short screening instrument was identified for the first time as an independent predictor of all-cause mortality in hemodialysis patients. Thus, implementing the MoCA test in clinical routine could contribute to a better risk stratification of this patient population.