Factors Associated with Frailty Transitions Using the Kihon Checklist: A 6-Year Longitudinal Study Among Japanese Residents

Abstract

Background: The Kihon Checklist (KCL) is widely used in Japan to assess robustness, pre-frailty, and frailty. However, the specific KCL items that predict the maintenance of robustness or transitions between frailty states remain unclear. Identifying these predictors could guide preventive strategies in older adults. This study examined item-level predictors of frailty transitions in a community-dwelling population over 6 years. Methods: This longitudinal non-interventional study followed residents aged 70 years in 2016 and 76 years in 2022 in Agano City, Japan. Health status was evaluated using the 25-item KCL, and frailty states (robust, pre-frail, frail) were classified by total scores. Changes in responses to each item (yes-to-yes, yes-to-no, no-to-yes, no-to-no) were analyzed. Multivariate logistic regression identified independent predictors of maintaining robustness, transitioning to pre-frailty or frailty, and improving from frailty. Results: Among the 358 participants that completed both surveys, robustness decreased from 60.9% to 48.6%. Maintaining robustness was independently associated with visiting friends and absence of fear of falling. Transition to pre-frailty was linked with loss of stair-climbing ability, difficulty eating tough foods, and impaired date orientation. Transition to frailty was associated with persistently low body mass index, reduced outings, memory loss recognized by others, and difficulty performing routine tasks. Improvement from frailty was predicted by initiating weekly outings. Conclusion: Key protective factors included social engagement, absence of fear of falling, oral function, cognitive health, and maintaining body weight. Regular outings prevented frailty and facilitated recovery, highlighting practical community-level intervention targets. Future research should test whether programs targeting these predictors reduce frailty incidence and improve recovery.