Validation of the Japanese version of the Clinical Frailty Scale

Among the many screening tools developed to detect frailty and disability in older adults, the Clinical Frailty Scale (CFS) is a valid, reliable, and easy-to-use tool and has been translated into several languages. The aim of this study was to demonstrate the validity of the Japanese version of the CFS (CFS-J).

The necessary permissions were obtained from Rockwood and colleagues. The Japanese version was prepared by translation (English to Japanese) and verified by back translation (Japanese to English). Concurrent criterion validity was assessed by evaluating the extent to which CFS relates to the Frailty Index (FI), the Frailty Index based on a Comprehensive Geriatric Assessment (FI-CGA), and Performance Status (PS), using Kendall's tau.

In total, 223 patients admitted to the geriatric ward of an acute hospital between June 2021 and March 2023 were analyzed in the validation study. Mean age was 84.9 ± 5.9 years (range, 67-101 years), 128 (57.4%) were women, and the mean body mass index was 20.9 ± 4.0 kg/m². In a correlation analysis, significantly positive associations were found between the CFS-J and the FI (r = 0.713, P < 0.001), the FI-CGA (r = 0.691, P < 0.001), and PS (r = 0.669, P < 0.001) for numerical variables. Significant positive associations were also found between the CFS-J and the FI (r = 0.567, P < 0.001) and the FI-CGA (r = 0.591, P < 0.001) for categorical valuables.

The CFS-J was found to be a valid instrument for identifying frailty in Japanese inpatients. Geriatr Gerontol Int 2025; 25: 411-417.