Assessing Functional Cognition in People on Maintenance Hemodialysis Using Performance-Based Testing

Key Points. Approximately half of people on maintenance hemodialysis exhibited impairment on a standardized, performance-based assessment of functional cognition.
The functional cognitive test correlated strongly with a traditional cognitive screening tool but weakly with self-report functional assessments.
Older age and ethnic minority were significant predictors of functional cognitive impairment.
Background. People on maintenance hemodialysis are often unable to perform everyday activities without assistance. The extent to which their functional limitations are related to cognitive impairment is unclear. Our primary aim was to estimate the proportion of people on maintenance hemodialysis who demonstrate impairment on a standardized, performance-based test of functional cognition.
Methods. We conducted a quantitative descriptive, cross-sectional study across two dialysis centers in Toronto, Canada. We administered a functional cognitive assessment (University of California San Diego Performance-Based Skills Assessment-Brief [UPSA-B]), a cognitive screening tool (Montreal Cognitive Assessment [MoCA]), and two self-report measures of everyday functioning (Barthel Index and Lawton-Brody Instrumental Activities of Daily Living [IADL] scale) during the first hour of a hemodialysis session. We calculated the proportion of participants with UPSA-B scores indicating functional cognitive impairment (<78). We also calculated correlations between the UPSA-B and the MoCA, Barthel Index, and Lawton-Brody IADL scale and used multivariable logistic regression to explore predictors of impairment on the UPSA-B.
Results. One hundred and five people on hemodialysis consented to participate. The mean age was 68 (12) years, 71% were male, and the median dialysis vintage was 36 months. 56 (54%) participants displayed impairment on the UPSA-B (95% confidence interval [CI], 44% to 64%). There was a strong correlation between the UPSA-B and the MoCA (r=0.67, P < 0.001) and weak correlations between the UPSA-B and the Barthel Index (r=0.38, P < 0.001) and Lawton-Brody IADL scale (r=0.39, P < 0.001). Older age (odds ratio, 1.13; 95% CI, 1.07 to 1.20) and ethnicity (odds ratio, 17.8; 95% CI, 4.71 to 67.50) were significant predictors of impairment on the UPSA-B in multivariable modeling.
Conclusions. Functional cognitive impairment appears to be common in people on hemodialysis. Future research should investigate approaches such as cognitive rehabilitation to support everyday functioning in this population.