Cognitive impairment in hemodialysis patients is common

Background: Hemodialysis patients are at high risk for cognitive impairment due to their older age and high prevalence of stroke and cardiovascular risk factors. Methods: Using a cross-sectional design, the authors measured cognitive function in 374 hemodialysis patients aged 55 years and older and an age-matched comparison group in Minneapolis and St. Paul, MN. Cognitive performance was measured in three domains: memory, executive function, and language. Subjects were classified as having no, mild, moderate, or severe cognitive impairment. Results: Of 338 subjects who completed testing in at least two of the three cognitive domains, 13.9% (95% CI 10.4, 18.1) were classified with mild impairment, 36.1% (31.0, 41.5) with moderate impairment, 37.3% (32.1, 42.7) with severe impairment, and 12.7% (9.4, 16.8) with normal cognition. Only 2.9% had a documented history of cognitive impairment. Factors associated with severe cognitive impairment on adjusted logistic regression were stroke (adjusted OR [AOR] 1.95; 95% CI 1.08, 3.49; p < 0.03), equilibrated Kt/V > 1.2 (1.67; 1.01, 2.75; p < 0.05), and education > 12 years ( 0.32; 0.14, 0.72; p < 0.01). The AOR for severe cognitive impairment in a random sample of 101 hemodialysis patients vs an age-matched comparison group was 3.54 (1.28, 9.78; p < 0.02). Conclusions: Moderate to severe cognitive impairment is common and undiagnosed in hemodialysis patients. Further studies are needed to determine whether dialysis exacerbates the cognitive impairment attributable to underlying disease. Cognitive testing in hemodialysis patients before dialysis initiation and periodically may be warranted.