Claimed-based frailty index in Japanese older adults: a cohort study using LIFE Study

Backgrounds: We aimed to assess whether the U.S. developed claimed-based frailty index (CFI) can be implemented in Japanese older adults using claim data.Methods: We used the monthly claims data and certification of long-term care (LTC) insurance data of residents from 12 municipalities from April 2014 to March 2019. The 12 months from first recording was defined as the "baseline period," and the time thereafter as "follow-up period". Participants aged >= 65 years and those with no certified LTC insurance or who died at baseline were included. New certification of LTC insurance and all-cause mortality during the follow-up period were defined as outcome events. CFI categorization consisted of three steps including: 1) using 12 months deficit-accumulation approach that assigned different weights to each of the 52 items; 2) the accumulated score to derive the CFI; and 3) categorizing the CFI as "robust" (<0.15), "prefrail" (0.15-0.24), and "frail" (>= 0.25). Kaplan-Meier survival curves and Cox proportional hazard models were used to determine the association between CFI and outcomes. Hazard ratios (HR) and 95% confidence intervals (95%CI) were calculated.Results: The participants were 519,941 in total. After adjusting for covariates, the severe CFI category had a high risk of certification of LTC insurance (prefrail, HR: 1.33, 95%CI:1.27-1.39; frail, HR: 1.60, 95%CI: 1.53-1.68) and all-cause mortality (prefrail, HR: 1.44, 95%CI: 1.29-1.60; frail, HR: 1.84, 95%CI: 1.66-2.05).Conclusions: This study suggests that CFI can be implemented in Japanese claims data by predicting the certification of LTC insurance and mortality.