Cognitive Impairment and Progression of CKD

Background: Cognitive impairment is common among patients with chronic kidney disease (CKD); however, its prognostic significance is unclear. We assessed the independent association between cognitive impairment and CKD progression in adults with mild to moderate CKD. Study Design: Prospective cohort. Setting & Participants: Adults with CKD participating in the CRIC (Chronic Renal Insufficiency Cohort) Study. Mean age of the sample was 57.7 ± 11.0 years and mean estimated glomerular filtration rate (eGFR) was 45.0 ± 16.9 mL/min/1.73 m². Predictor: Cognitive function was assessed with the Modified Mini-Mental State Examination at study entry. A subset of participants 55 years and older underwent 5 additional cognitive tests assessing different domains. Cognitive impairment was defined as a score > 1 SD below the mean score on each test. Covariates included demographics, kidney function, comorbid conditions, and medications. Outcomes: Incident end-stage renal disease (ESRD) and incident ESRD or 50% decline in baseline eGFR. Results: In 3,883 CRIC participants, 524 (13.5%) had cognitive impairment at baseline. During a median 6.1 years of follow-up, 813 developed ESRD and 1,062 developed ESRD or a ≥50% reduction in eGFR. There was no significant association between cognitive impairment and risk for ESRD (HR, 1.07; 95% CI, 0.87-1.30) or the composite of ESRD or 50% reduction in eGFR (HR, 1.06; 95% CI, 0.89-1.27). Similarly, there was no association between cognitive impairment and the joint outcome of death, ESRD, or 50% reduction in eGFR (HR, 1.06; 95% CI, 0.91-1.23). Among CRIC participants who underwent additional cognitive testing, we found no consistent association between impairment in specific cognitive domains and risk for CKD progression in adjusted analyses. Limitations: Unmeasured potential confounders, single measure of cognition for younger participants. Conclusions: Among adults with CKD, cognitive impairment is not associated with excess risk for CKD progression after accounting for traditional risk factors.