Risk for cognitive impairment across 22 measures of cognitive ability in early-stage chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is a significant risk factor for cognitive impairment. Previous studies have examined differences in cognitive impairment between persons with and without CKD using multiple cognitive outcomes, but few have done this for an extensive battery of cognitive tests. We relate early-stage CKD to two indices of impairment for 22 measures of cognitive ability.

METHODS: The study was community-based and cross-sectional with 898 individuals free from dementia and end-stage renal disease. Estimated glomerular filtration rate (eGFR) was calculated using the chronic kidney disease epidemiology collaboration equation and classified as <60 or ≥60 mL/min/1.73 m(2), based on consensus definitions of Stage 3 or greater CKD. The eGFR classifications were related to modest [≥1 standard deviation (SD) below the mean] and severe (≥1.5 SD below the mean) impairment on each measure using logistic regression analyses adjusting for potential risk factors.

RESULTS: A total of 146 individuals (16.3%) had eGFR <60 mL/min/1.73 m(2) (mean 51.6 ± 10.1 mL/min/1.73 m(2)). These participants had significantly greater risk for modestly impaired abilities in the scanning and tracking and visual-spatial organization/memory (VSOM) domains after accounting for comorbidity-related risk factors [odds ratios (ORs) between 1.68 and 2.16], as well as greater risk for severely impaired functioning in the language domain (OR = 2.65).

CONCLUSIONS: Participants with eGFR <60 mL/min/1.73 m(2) were at higher risk for cognitive impairment than those with eGFR ≥60 mL/min/1.73 m(2) on the majority of cognitive abilities, specifically those within the VSOM, Language, and scanning and tracking domains. Targeted screening for cognitive deficits in kidney disease patients early in their disease course may be warranted.