Relationship between longitudinal measures of renal function and onset of dementia in a community cohort of older adults.

OBJECTIVES: To evaluate the association between dynamic measures of renal function ascertained over time and onset of dementia.
DESIGN: Prospective community cohort study.
SETTING: Group Health, Seattle, Washington. PARTICIPANTS: Two thousand nine hundred sixty-eight adults aged 65 and older followed for the development of dementia over a median of 6.0 years (interquartile range 3.1-10.1 years). MEASUREMENTS: Time-varying measures of renal function were constructed based on 49,340 serum creatinine measurements and included average estimated glomerular filtration rate (eGFR), eGFR trajectory, and variability in eGFR around this trajectory over 5-year exposure windows. The association between these three eGFR exposure measures and risk of dementia was estimated using a Cox regression model adjusted for other participant characteristics. Time-varying measures of urine protein by dipstick were also adjusted for in sensitivity analyses.
RESULTS: Participants with a lower eGFR had a higher incidence of dementia, but this did not reach statistical significance in adjusted analyses (omnibus P = .14). There were trends toward a higher adjusted incidence of dementia in participants with positive eGFR trajectories (omnibus P = .07) and greater variability in eGFR (omnibus P = .04) over time. The results of sensitivity analyses, including those in which time-varying measures of proteinuria were included, were consistent with those of the primary analysis.
CONCLUSION: In a community cohort of older adults followed for a median of 6 years, strong associations were not found between measures of kidney disease severity and progression and incident dementia.