Prevalence and correlates of cognitive impairment in hemodialysis patients: the Frequent Hemodialysis Network trials

Abstract

Background and objectives: Cognitive impairment is common among persons with ESRD, but the underlying mechanisms are unknown. This study evaluated the prevalence of cognitive impairment and association with modifiable ESRD- and dialysis-associated factors in a large group of hemodialysis patients.

Design, setting, participants, & measurements: Cross-sectional analyses were conducted on baseline data collected from 383 subjects participating in the Frequent Hemodialysis Network trials. Global cognitive impairment was defined as a score <80 on the Modified Mini-Mental State Exam, and impaired executive function was defined as a score >or=300 seconds on the Trailmaking B test. Five main categories of explanatory variables were examined: urea clearance, nutritional markers, hemodynamic measures, anemia, and central nervous system (CNS)-active medications.

Results: Subjects had a mean age of 51.6 +/- 13.3 years and a median ESRD vintage of 2.6 years. Sixty-one subjects (16%) had global cognitive impairment, and 110 subjects (29%) had impaired executive function. In addition to several nonmodifiable factors, the use of H1-receptor antagonists and opioids were associated with impaired executive function. No strong association was found between several other potentially modifiable factors associated with ESRD and dialysis therapy, such as urea clearance, proxies of dietary protein intake and other nutritional markers, hemodynamic measures, and anemia with global cognition and executive function after adjustment for case-mix factors.

Conclusions: Cognitive impairment, especially impaired executive function, is common among hemodialysis patients, but with the exception of CNS-active medications, is not strongly associated with several ESRD- and dialysis-associated factors.

Figure 1.

Derivation of the analytic cohort.

Figure 2.

Scatterplot of scores on 3MS and Trails B. Dashed lines indicate test cut points for cognitive impairment.

Figure 3.

Prevalence of cognitive impairment by decade of age. Note that global cognitive impairment was defined as a score <80 on the 3MS and impaired executive function was defined as a score ≥300 seconds on the Trails B test.