Glomerular filtration rate proteinuria and risk of dementia: a cohort study from the national health insurance database

Abstract

AbstractBackgroundThe previous studies had shown conflicting results about the association between kidney dysfunction and dementia. One of the causes may be the use of different indicators to define kidney dysfunction. Although estimated glomerular filtration rate (eGFR) and proteinuria reflect the kidney’s different aspects, few studies used both indicators to examine the association between kidney dysfunction and dementia. In addition, even in the same study, the correlation between kidney dysfunction and dementia was different depending on the indicator. We aimed to demonstrate the association between kidney dysfunction and dementia using renal indicators‐ eGFR and proteinuria independently or together.MethodWe used the National Health Insurance database covering the entire population in South Korea to identify and follow up with the population who checked up in the National Health Screening Program (NHSP) from January 2009 to December 2010. Dementia was defined as a newly diagnosed dementia among the population without a history of dementia before enrollment. We used Cox proportional hazard model to examine between eGFR or proteinuria and the risk of dementia.ResultThere were 283,747 incident dementia cases during 132,811,487 person‐years of follow‐up. The risk of dementia was progressively higher with lower eGFR; compared to eGFR≥100 mL/min, hazard ratio (HR) 1.09, confidence interval [CI], 1.07‐1.12 in eGFR 90‐100 mL/min, HR 1.08, 95% CI, 1.06‐1.10 in eGFR 60‐90 mL/min, HR 1.22, 95% CI, 1.19‐1.24, in eGFR 30‐60 mL/min, HR 1.99, 95% CI, 1.86‐2.12 in eGFR 15‐30 mL/min, and HR 3.05, 95% CI, 2.96‐3.14 in eGFR <15 mL/min or dialysis. The proteinuria was also correlated with dementia (HR 1.25, 95% CI, 1.23‐1.27) after adjusting eGFR. Proteinuria contributed to the stratification of the high‐risk patients for dementia in each eGFR stratum; HR 1.39[95% CI, 1.26‐1.53]in eGFR ≥100 mL/min, HR 1.28[95% CI, 1.21‐1.35]in eGFR 90‐100 mL/min, HR 1.23[95% CI, 1.20‐1.27] in eGFR 60‐90 mL/min, HR 1.24[95% CI, 1.20‐1.28] in eGFR 30‐60 mL/min, HR 1.06[95% CI, 0.89‐1.26] in eGFR 15‐30 mL/min, and HR 1.16[95% CI, 1.10‐1.22] in eGFR <15 mL/min or dialysis.ConclusioneGFR and proteinuria were associated with dementia independently. The use of both eGFR and proteinuria was useful for the stratification of dementia risk.