Kidney Function and Physical Performance Decline: The Brain in Kidney Disease (BRINK) Cohort Study

Abstract

Rationale & Objective: Patients with kidney failure have poor physical performance, but its trajectory is less clear. We examined physical function over the course of kidney disease, including the transition to dialysis. Study Design: Observational cohort. Setting & Participants: Community-dwelling adults aged ≥45 years in the Brain in Kidney Disease (BRINK) cohort study. Predictors: Estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (UACR). Outcomes: Change in physical performance using the Short Physical Performance Battery (SPPB) (primary) and gait speed (secondary). Analytical Approach: Linear mixed effects regression models. Results: The analytical cohort included 562 participants with mean age of 69.3 (SD, 9.8) years followed for up to 63 months. In total, 49.8% were women. In addition, 79.9% self-identified as White, and 15.3% self-identified as Black. In total, 48.8% had diabetes. Mean eGFR at baseline was 48.1 (SD, 24.3) mL/min/1.73 m2. In unadjusted analysis, lower eGFR was associated with greater decline in SPPB score (P trend < 0.001). The decline in SPPB score was larger among participants with lower eGFR, with a gradient from -0.15 (95% CI, -0.23 to -0.07) points per year for participants with eGFR ≥60 mL/min/1.73 m2 to -0.56 (95% CI, -0.84 to -0.27) for participants with eGFR <15 mL/min/1.73 m2 and -0.61 (95% CI, -0.90 to -0.33) after dialysis initiation. In covariate-adjusted models, SPPB did not continue to decline after dialysis initiation. In secondary analyses evaluating change in gait speed, gait speed continued to decline after dialysis initiation. Higher UACR was also associated with a greater decline in SPPB score and gait speed in unadjusted and adjusted models. Limitations: Small number of participants started dialysis. Conclusions: We found a graded association of chronic kidney disease stage and albuminuria with decline in physical performance. The decline in SPPB was not accelerated after dialysis initiation in covariate-adjusted models, whereas gait speed continued to decline. Plain-Language Summary: Physical function is an important patient-centered outcome in chronic kidney disease (CKD), but whether physical performance changes as kidney disease progresses or when patients start dialysis is not well understood. We found that measures of physical performance, like strength and walking speed, worsened as kidney disease worsened. However, 1 combination of physical performance tests appeared stable (rather than getting worse) after starting dialysis compared to those with very advanced CKD who had not yet started dialysis, while gait speed continued to get worse. This information may help counsel patients who are learning about CKD and considering treatment options. It may also help guide research on interventions to improve physical function in patients with CKD.

Keywords

• Chronic kidney disease
• dialysis
• kidney disease progression
• physical function
• physical performance