Associations of Performance-Based Functional Assessments and Adverse Outcomes in Chronic Kidney Disease

Background: The comparative utility of performance-based functional assessments in predicting adverse outcomes in Chronic Kidney Disease (CKD) is unknown. We examined three performance-based functional assessments in an observational cohort of CKD patients to determine their relative utility. Methods: 350 participants with Stage II-V, pre-dialysis CKD were recruited. Participants were administered three performance-based functional assessments: Short Physical Performance Battery (SPPB), Modified Mini Mental Status Exam (M3SE), and Lawton Instrumental Activities of Daily Living (IADL). Scores were dichotomized based on the median and combined into a summary score. Outcomes included 50% glomerular filtration rate (GFR) reduction, end-stage kidney disease (ESKD), and death. Cox proportional hazards assessed the association of performance-based functional assessments with outcomes. Results: Compared to high performers, low SPPB performers had the highest adjusted rate of death, ESKD, or 50% reduction in GFR (HR: 1.96, 95% CI: 1.28, 2.99). Low SPPB had the strongest association with death when adjusted for multiple covariates (HR: 2.43, 95% CI: 1.36, 4.34). M3SE performance was not associated with any adverse outcome. None of the performance-based functional assessments were associated with ESKD, but a low IADL score was associated with a lower hazard ratio for ESKD or 50% decline GFR (HR: 0.49, 95% CI: 0.24, 1.00). Conclusions: Low SPPB score was the strongest predictor of death and all adverse outcomes as a composite. Future trials should determine if outcomes for CKD patients with poor physical performance and low SPPB scores are improved by targeted interventions.