Cognitive Changes in Peritoneal Dialysis Patients: A Multicenter Prospective Cohort Study

Rationale & Objective: Cognitive impairment is an independent predictor of technique failure and mortality in patients on peritoneal dialysis (PD) therapy. We investigated changes in cognitive function and factors associated with it in this population. Study Design: Multicenter prospective cohort study. Setting & Participants: 458 PD patients were enrolled and followed up for 2 years. Predictors: Global and specific domains of cognitive function were measured at baseline and after 2 years. The Modified Mini-Mental State Examination (3MS) was used for assessment of global cognitive function; Trail-Making Tests A and B, for executive function; and subtests of the Battery for the Assessment of Neuropsychological Status, for immediate and delayed memory, visuospatial skill, and language ability. Outcomes: The primary outcome was change in cognitive function. Secondary outcomes included all-cause mortality, cardiovascular mortality, hospitalization, and transition to hemodialysis therapy. Analytical Approach: Multivariable linear regression models. Results: The prevalence of cognitive impairment increased from 19.8% to 23.9%. 3MS scores significantly decreased (84.8 to 83.1), although executive function, immediate memory, and visuospatial skill improved over time. Delayed memory capacity and language ability were unchanged. Lower serum albumin level was associated with deteriorated delayed memory, visuospatial skill, and language ability, as well as with the decline in general cognitive function (beta values of 0.64, 0.90, 0.80, and 0.44, respectively). Advanced age, lower education, and depression were also correlated with deterioration in general and specific cognitive function. After multivariable adjustment, both global and specific cognitive impairment at baseline were associated with a greater rate of hospitalization, and memory dysfunction was associated with a lower dialysis modality survival rate. Limitations: A relatively short observation period, small number of deaths, and potential selection bias due to patients unavailable for the second assessment. Conclusions: In a PD population, global cognitive function declined over 2 years, though some specific cognitive domains improved. Besides well-recognized factors, hypoalbuminemia and depression were also risk factors for cognitive impairment.