Supplementary Material for: Association of Albuminuria and Estimated Glomerular Filtration Rate with Functional Performance Measures in Older Adults with Chronic Kidney Disease

Background: Chronic kidney disease (CKD) is increasingly common and disproportionately affects older adults. The contribution of kidney disease to the functional impairment noted in the elderly CKD population is unclear. Methods: This is a cross-sectional analysis of a hypertensive cohort of people aged ≥75 years from the Systolic Blood Pressure Intervention Trial. We evaluated estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) as predictors of 3 measures of functional status: EuroQol-5 Dimensional (EQ-5D) score, Falls Efficacy Scale (FES) score, and gait speed. Linear regression models were used to evaluate the associations between our independent variables and outcome measures. Results: Our analysis included 2,620 participants, mean age of 79.9 (4.0) years. Unadjusted models showed that lower eGFR level and higher UACR level were associated with lower EQ-5D (p < 0.001 for both) and slower gait speed (p < 0.001 for both) and worse scores on FES (p = 0.032 and p = 0.039). In the fully adjusted models, higher levels of UACR remained significantly associated with lower EQ-5D scores and slower gait speed (p = 0.011 and p = 0.002, respectively). In contrast, level of eGFR was not associated with any functional outcome measures when accounting for covariates. Conclusions: In individuals aged ≥75 years, albuminuria and eGFR were associated with impairments in physical performance and self-reported functional status; however, only the association with albuminuria remained after adjusting for relevant demographics and comorbidities. Evaluation of albuminuria may provide an additional tool for identifying older individuals at risk for functional impairment.