Patients with end-stage renal disease (ESRD) on dialysis and patients who have received a kidney transplant may experience cognitive impairment, negatively affecting activities of daily living, quality of life, regimen adherence, healthcare costs, morbidity, and mortality. The treatment of choice for ESRD is kidney transplantation, which is associated with improved survival and quality of life.
Patients seeking to be put on the transplant list must undergo an evaluation process that includes multiple tests and clinic visits. Cognitive impairment can influence physicians’ perceptions and patients’ ability to complete the pretransplant evaluation. There are few data available on the association of eligibility for kidney transplant and cognition. Early detection of cognitive impairment can identify patients needing additional support or more detailed instructions as they work through the evaluation process.
Aditi Gupta, MD, and colleagues conducted a single-center longitudinal cohort study to examine how cognitive impairment is associated with the likelihood of being listed and time to listing for kidney transplant. Results of the study were reported in the Clinical Journal of the American Society of Nephrology [2019;14(4):567-575].
At the initial visit for evaluation for kidney transplant, the Montreal Cognitive Assessment (MoCA) was used to screen patients with ESRD for cognitive impairment. Patients were followed longitudinally for transplant eligibility, performed as a quality improvement project.
Exclusion criteria were any hearing or visual impairment that precluded taking the MoCA, inability to read, write, speak, or understand English, a previous chart diagnosis of dementia or mental retardation, or uncontrolled psychosis or active seizure disorder.
A total of 349 patients had MoCA assessment at the first visit and were included in the current analysis. Of those, 55% (n=193) had cognitive impairment (MoCA score <26). Mean age of the total cohort was 54 years, 42% (n=147) were men, and 73% (n=254) were white.
The patients were stratified into three groups based on their MoCA scores: severe cognitive impairment, MoCA ≤18 (n=21); mild-to-moderate cognitive impairment, MoCA 19-25 (n=172); and no cognitive impairment, MoCA ≥26 (n=156). There were differences in age, race, and history of smoking between those with no cognitive impairment and those with cognitive impairment. Those with cognitive impairment were older (62 and 55 years versus 51 years, respectively) and a higher proportion was nonwhite (4% and 46% versus 50%, respectively), than those with no cognitive impairment.
There were no differences among the three groups in time on dialysis or cause of ESRD. However, among patients with ESRD secondary to polycystic disease, a higher proportion of patients had normal cognition (MoCA ≥26; P=.01).
A higher proportion of black patients had cognitive impairment compared with white patients (69% vs 50%, respectively; P<01). The researchers analyzed this subgroup to determine whether a difference in age led to the difference in MoCA score. Black patients in the cohort were younger than the white patients (P=.02) and had lower MoCA scores compared with white patients.
Results of Kaplan-Meier analysis found that patients with higher MoCA scores were listed earlier; there was clear delineation between the three subgroups. When divided further by age and MoCA score, it took longer for active listing for patients with cognitive impairment than for those with no cognitive impairment in that age group with the exception of patients <50 years of age. Median time to active listing was higher for those with cognitive impairment compared with patients with no cognitive impairment (10.6 months vs 6.3 months). Patients with cognitive impairment were declared ineligible sooner than those without cognitive impairment (8.6 months vs 15.4 months).
In the Cox proportional hazards model, MoCA score, sex, race, smoking, and diabetes were significant covariates associated with time to listing. There was an association between lower MoCA score and lower chances of active listing. Older patients and women also had a lower likelihood of listing.
By the end of 1 year after the initial pretransplant evaluation, 23.3% of patients with cognitive impairment were listed for transplant or had received a transplant, compared with 41% of patients with no cognitive impairment. Further, 43% of patients with cognitive impairment were declared ineligible or removed from the waitlist, compared with 32% of those with no cognitive impairment. There were no differences between patients who were declared ineligible within a month of the initial evaluation and those who were declared ineligible after a month, with the exception of a shorter time on dialysis for patients with mild-to-moderate cognitive impairment who were declared ineligible within a month (P<.01).
Study limitations cited by the authors included limiting the definition of cognitive impairment to results of the MoCA screening test rather than a detailed assessment of cognition with multiple neuropsychologic tests; using chart review to obtain medical history; and the single-center design of the study.
“In conclusion, cognitive impairment is common in patients presenting for transplant evaluation. Increasing age, history of smoking, and nonwhite race/ethnicity are associated with pretransplant cognitive impairment. Pretransplant cognition is associated with transplant eligibility. Cognitive impairment is associated with a lower likelihood of being listed for kidney transplant, and it is associated with a longer time to listing. Additional understanding of the reasons why cognitive impairment influences time to listing may improve transplant eligibility,” the researchers said.
- Researchers at the University of Kansas Medical Center conducted a single-center longitudinal study to examine the influence of cognitive impairment on the likelihood for transplant listing and whether patients with cognitive impairment take longer to be declared eligible for listing.
- Montreal Cognitive Assessment scores were used to stratify patients into three groups: no cognitive impairment, mild-to-moderate cognitive impairment, and severe impairment. The time to listing for those in the cognitive impairment groups was longer than for patients with no cognitive impairment (10.6 vs 6.3months; P=.01).
- There was an independent association between cognitive impairment and a lower likelihood of being listed. At all study time points, a lower proportion of patients in the cognitive impairment groups were listed compared with patients without cognitive impairment.