A 10-Item Frailty Index Based on a Comprehensive Geriatric Assessment (FI-CGA-10) in Older Adults with Cancer: Development and Construct Validation

Background A frailty index (FI) based on domain-level deficits identified through a comprehensive geriatric assessment (CGA) has been previously developed and validated in general geriatric patients. Our objectives were to construct an FI-CGA and to assess its construct validity in the geriatric oncology setting. Methods Five hundred forty consecutive Japanese patients with cancer who underwent a CGA on a geriatric oncology service were included (median age 80 years, range 66-96 years). We developed a 10-item frailty index based on deficits in 10 domains (FI-CGA-10): cognition, mood, communication, mobility, balance, nutrition, basic and instrumental activities of daily living, social support, and comorbidity. Deficits in each domain were scored as 0 (no problem), 0.5 (minor problem), and 1.0 (major problem). Scores were calculated by dividing the sum of the scores for each domain by 10 and then categorized as fit (<0.2), pre-frail (0.2-0.35), and frail (>0.35). Construct validity was tested by correlating the FI-CGA-10 with other established frailty measures. Results FI-CGA-10 was well approximated by the gamma distribution. Overall, 20% of patients were fit, 41% were pre-frail, and 39% were frail. FI-CGA-10 was correlated with Canadian Study of Health and Aging (CSHA) Clinical Frailty Scale (r = 0.83), CSHA rules-based frailty definition (r = 0.67), and CSHA Function Score (r = 0.77). Increasing levels of frailty were significantly associated with functional and cognitive impairments, high comorbidity burden, poor self-rated health, and low estimated survival probabilities. Conclusion The FI-CGA-10 is a user-friendly and construct-validated measure for quantifying frailty from a CGA. Implications for Practice This article describes the construction of a user-friendly 10-item frailty index based on a comprehensive geriatric assessment (FI-CGA-10) for older adults with cancer: cognition, mood, communication, mobility, balance, nutrition, basic and instrumental activities of daily living, social support, and comorbidity. The FI-CGA-10 simplifies the original FI-CGA used in the general geriatric setting while maintaining its content validity. The index's construct validity was demonstrated in a cohort of older adults with various cancer types. The advantage of the FI-CGA-10 is that a frailty score can be calculated more readily and interpreted in a more clinically sensible manner than the original FI-CGA.