Impact of Cognitive Function Change on Mortality in Renal Transplant and End-Stage Renal Disease Patients

Background: Limited evidence from small-scale studies, mainly involving end-stage renal disease (ESRD) patients, suggests that kidney transplantation may improve cognitive function. We examined changes in cognitive function after a kidney transplant and its association with survival in advanced chronic kidney disease (CKD)/ESRD patients. Methods: In a prospective study design, cognitive performance of 90 patients (50.6 ± 13.1 years, 66.7% men, 27.8% blacks, 76% CKD stages 4-5) was assessed at the respective patients' residences using established neurocognitive tests. Results: Among the 90 patients, 44 received a kidney transplant (KTx group) while 46 did not (no-KTx group). After a mean follow-up of ∼19 months, there was no significant change in scores for majority of cognitive tests in either group. Older age, but not diabetes or renal function status (CKD vs. ESRD), was a determinant of poor follow-up cognitive performance. Additionally, poor attention/psychomotor speed and executive performance (as measured by Trails A and Stroop test, respectively) was associated with higher mortality over a mean follow-up of 4.7 years, even after adjustment for age, sex, diabetes, CKD or ESRD status and kidney transplant status. Conclusion: Overall, cognitive function does not significantly improve after kidney transplant or significantly decline in non-transplanted, advanced CKD/ESRD patients. Poor attention, psychomotor speed and executive performance independent of transplant status were associated with higher mortality over time.