Kidney function and cognitive decline in an oldest-old Chinese population.

BACKGROUND: Early-stage chronic kidney disease has been suggested to be correlated with cognitive decline, but the association has rarely been explored in the oldest old.

SUBJECTS AND METHODS: This prospective study included 284 Chinese participants aged 80 years or older with serum creatinine levels <150 µmol/L. The median follow-up time was 3.3 years, and 247 (87.0%) participants provided valid data at their last visit. Kidney function was evaluated by measuring the estimated glomerular filtration rate (eGFR) at baseline, and cognitive function was evaluated using the Mini-Mental State Examination (MMSE) at both baseline and annual visits. A reliable decrease in the MMSE score over the follow-up period was observed based on a Reliable Change Index of 1.645 (equivalent to a 90% confidence interval [CI]), which was used to define cognitive decline. Poisson regression models were built to analyze the association between baseline kidney function and cognitive decline.

RESULTS: A total of 18 (7.3%) cases of incident cognitive decline were observed during the follow-up period. After adjusting for potential confounders, the relative risk of developing cognitive decline was 4.03 (95% CI 1.09-13.81) among participants with an eGFR of 30-59 mL/min/1.73 m2 compared to participants with an eGFR of ≥60 mL/min/1.73 m2 .

CONCLUSION: Early-stage chronic kidney disease was correlated with cognitive decline in an oldest-old Chinese population.