Aging Clinical and Experimental Research · May 5, 2016
The relative and absolute reliability of the Functional Independence and Difficulty Scale in community-dwelling frail elderly Japanese people using long-term care insurance services
By Saito T, Izawa KP, Watanabe S
BACKGROUND: The newly developed Functional Independence and Difficulty Scale is a tool for assessing the performance of basic activities of daily living in terms of both independence and difficulty. The reliability of this new scale has not been assessed. AIMS: The aim of this study was to examine the relative reliability and absolute reliability of the newly developed scale in community-dwelling frail elderly people in Japan. METHODS: Participants were 47 community-dwelling elderly subjects (22 for assessing test-retest reliability and 25 for assessing inter-rater reliability). As relative reliability indices, intra-class correlation coefficients were used. From an absolute reliability perspective, we conducted Bland-Altman analysis and calculated the limit of agreement or minimal detectable change to determine the acceptable range of error. RESULTS: Intra-class correlation coefficients for test-retest and inter-rater reliability were 0.90 (P < 0.001) and 0.97 (P < 0.001), respectively. The limit of agreement for test-retest reliability was -5.2 to 1.8, representing an increase of over six points for improvement and a decrease of over two points for decline of basic activities of daily living ability. The minimal detectable change for inter-rater reliability was 3.7, indicating that a three-point difference might be existed between difference raters. The results of this study demonstrated that the FIDS appeared to be a reliable instrument for use in Japanese community-dwelling frail elderly people. CONCLUSIONS: While further research using a large and more diverse sample of participants is needed, our findings support the use of FIDS in clinical practice or clinical research targeting frail elderly Japanese people.