Developing a new frailty index for Korean elderly population: comparison of outcome and prevalence of frailty with existing phenotype models

Abstract

Background: Frailty is related to adverse outcomes in the elderly. However, current status and clinical significance of frailty has not been evaluated for the Korean elderly population. We aimed to investigate the usefulness of established frailty criteria for community-dwelling Korean elderly. We also tried to develop and validate a new frailty index based on a multidimensional model. Methods: We studied 693 participants of the Korean Longitudinal Study on Health and Aging (KLoSHA). We developed a new frailty index (KLoSHA Frailty Index, KFI) and compared predictability of it with the established frailty indexes from the Cardiovascular Health Study (CHS) and Study of Osteoporotic Fracture (SOF). Mortality, hospitalization, and functional decline were evaluated. Results: The prevalence of frailty was 9.2% (SOF index), 13.2% (CHS index), and 15.6% (KFI). Frailty status by CHS and KFI correlated with each other, but SOF did not correlate with KFI. During the follow-up period (5.6 ± 0.9 years), 97 participants (14.0%) died. Frailty defined by KFI predicted mortality better than CHS index (c-index: 0.713 and 0.596, respectively

p<0.001, better for KFI). In contrast, frailty by SOF index was not related to mortality. The KFI showed better predictability for following functional decline than CHS index (area under the receiver-operating characteristic curve was 0.937 for KFI and 0.704 for CHS index, p=0.001). However, the SOF index could not predict subsequent functional decline. Frailty by the KFI (OR=2.13, 95% CI 1.04-4.35) and CHS index (OR=2.24, 95% CI 1.05-4.76) were significantly associated with hospitalization. In contrast, frailty by the SOF index was not significantly correlated with hospitalization (OR=1.43, 95% CI 0.68-3.01). Conclusions: Prevalence of frailty was higher in Korea compared to previous studies in other countries. A novel frailty index (KFI), which includes domains of comprehensive geriatric assessment, is a valid criterion for the evaluation and prediction of frailty in the Korean elderly population.