Cognitive impairment assessments in kidney transplantation: A review

Mild cognitive impairment (CI) is not an absolute contraindication for kidney transplantation (KT). However, clinical assessment has not been standardized, and several practice challenges remain. We synthesized existing evidence on the effect of CI on adult kidney transplant recipients (KTRs) and KT candidates. Of the 1333 titles and abstracts screened, seven studies were eligible; all were observational. Our synthesis included 1035 KTRs and 4659 patients being evaluated for KT. Studies that used the Montreal Cognitive Assessment (38-55 %) reported a higher CI prevalence than those that used the Modified Mini-Mental State Exam (6-10 %). CI decreased the chances of KT waitlisting, however, the association with KT, graft loss and death varied by the cohort characteristics and tests used. The implications of our synthesis are limited by selection bias due to the exclusionary criterion, variability in tests and thresholds used. This may have misclassified participants with normal cognition as having CI and included those with dementia. Overall, additional evidence is needed to standardize the cognitive assessment of KTRs and candidates and inform clinical practice. A comprehensive assessment of cognition and function is indicated for the accurate diagnosis of CI, to determine CI severity, and to assess transplant candidacy.