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Validation of a Claims-Based Frailty Index Against Physical Performance and Adverse Health Outcomes in the Health and Retirement Study


Kim, D., Glynn, R., Avorn, J., Lipsitz, L., Rockwood, K., Pawar, A., and Schneeweiss, S.


Journals of Gerontology Series A: Biological Sciences and Medical Sciences




Background: A claims-based frailty index (CFI) was developed based on a deficit-accumulation approach using self-reported health information. This study aimed to independently validate the CFI against physical performance and adverse health outcomes.

Methods: This retrospective cohort study included 3,642 community-dwelling older adults who had at least 1 health care encounter in the year prior to assessments of physical performance in the 2008 Health and Retirement Study wave. A CFI was estimated from Medicare claims data in the past year. Gait speed, grip strength, and the 2-year risk of death, institutionalization, disability, hospitalization, and prolonged (>30 days) skilled nursing facility (SNF) stay were evaluated for CFI categories (robust: <0.15, prefrail: 0.15-0.24, mildly frail: 0.25-0.34, moderate-to-severely frail: ≥0.35).

Results: The prevalence of robust, prefrail, mildly frail, and moderate-to-severely frail state was 52.7%, 38.0%, 7.1%, and 2.2%, respectively. Individuals with higher CFI had lower mean gait speed (moderate-to-severely frail vs robust: 0.39 vs 0.78 m/s) and weaker grip strength (19.8 vs 28.5 kg). Higher CFI was associated with death (moderate-to-severely frail vs robust: 46% vs 7%), institutionalization (21% vs 5%), activity of daily living disability (33% vs 9%), instrumental activity of daily living disability (100% vs 22%), hospitalization (79% vs 23%), and prolonged SNF stay (17% vs 2%). The odds ratios per 1-SD (=0.07) difference in CFI were 1.46-2.06 for these outcomes, which remained statistically significant after adjustment for age, sex, and a comorbidity index.

Conclusion: The CFI is useful to identify individuals with poor physical function and at greater risks of adverse health outcomes in Medicare data.

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