Frailty Assessment Tools in Chronic Kidney Disease: A Systematic Review and Meta-analysis.

Rationale & Objective: Frailty represents a loss of physiologic reserve across multiple biological systems, confers a higher risk of adverse health outcomes, and is highly prevalent among people with chronic kidney disease (CKD). We evaluated the measurement properties of frailty tools used in CKD and summarized the association of frailty with death and hospitalization. Study Design: Systematic review and meta-analysis. Setting & Study Populations: Studies assessing multidimensional frailty tools in adults at any stage of CKD and evaluating a measurement property of interest as per the Consensus-based Standards for the Selection of Health Measurement Instruments taxonomy. Selection Criteria for Studies: Observational studies and randomized trials. Data Extraction: Risk and precision measurements; measurement properties. Analytical Approach: The Comprehensive Geriatric Assessment was the clinical standard for frailty identification. We pooled data using random effects models or summarized with narrative synthesis when data were too heterogenous to pool. Results: We included 105 studies with data for at least one of the following: discriminative (n = 84; 80%), convergent (n = 20; 19%), and criterion validity (n = 2; 2%); responsiveness (n = 9; 9%) and reliability (n = 1; 0.1%). For the Fried Frailty Phenotype (FFP), the pooled adjusted HR (aHR) for mortality was 2.01 (95% confidence intervals [CI], 1.35-2.98; Limitations: Few studies compared the accuracy of frailty tools to the Comprehensive Geriatric Assessment. Only 1 study reported reliability. Studies were of overall low-moderate quality. Conclusions: The FFP and Clinical Frailty Scale showed acceptable discriminant validity for clinical outcomes, and the modified FFP is an alternative tool to use if direct measurements are not feasible. The evidence does not support the use of clinicians' subjective impression to identify frailty.