External Validation of the Claims-Based Frailty Index in the National Health and Aging Trends Study Cohort

Fried et al. (1) operationalized a frailty phenotype that can be reproducibly identified with standardized measures. The 5 measures that define the phenotype are unintentional weight loss, self-reported exhaustion, weakness as measured with grip strength, slow walking speed, and low physical activity. Individuals with this phenotype, however, cannot be easily identified in data that do not have these performance measures. Given the ubiquity of claims data, we recently developed a tool that we operationalized using claims data alone (2).