Cognitive Function Linked to Mortality in Hemodialysis Patients

Cognitive impairment, especially impaired executive function, is associated with an increased risk of death among patients receiving maintenance hemodialysis, reports a study in American Journal of Kidney Diseases.

The researchers analyzed the results of baseline and annual neurocognitive assessments in 292 patients receiving maintenance hemodialysis. The patients’ mean age was 63 years, and 90 percent had at least a high school education. Patients with dementia were excluded.

Associations between cognitive function and all-cause mortality were assessed, with adjustment for demographics and dialysis and cardiovascular (CV) risk factors. Test results were broken down into domain scores representing memory and executive function.

There were 145 deaths during a median follow-up time of 2.1 years. Each one SD increase in executive function score was associated with a 35 percent reduction in mortality—hazard ratio (HR) 0.65. The association remained significant after adjustment for demographics and dialysis-related factors (HR 0.81) but lost significance after adjustment for CV disease and heart failure. In time-dependent models, the unadjusted HR was 0.62, and the association remained significant after adjustment for demographic, dialysis, and CV factors (HR 0.79).

On univariate analysis, better memory scores were associated with lower mortality: HR 0.82 per one SD. However, this association became nonsignificant after adjustment for demographics.

Many hemodialysis patients have cognitive impairment, which is associated with increased morbidity. The new study shows that impaired performance on neurocognitive testing is associated with increased mortality. The association with memory appears to be explained by demographic factors, whereas the association with executive function may partly reflect the effects of CV disease. The authors call for new approaches to improving or stabilizing cognitive impairment in dialysis patients [Drew DA, et al. Cognitive function and all-cause mortality in maintenance hemodialysis patients. Am J Kidney Dis 2015; 65:303–311].