Functional Independence and Difficulty Scale: Instrument development and validity evaluation.

Aims: To validate the Functional Independence and Difficulty Scale, a new instrument that assesses both independence and difficulty in carrying out basic activities of daily living.

Methods: First, we developed an item list for our construct through a literature review. Second, an expert panel evaluated the item list using the modified Delphi method. Third, to evaluate psychometric properties, a random sample of 593 community-dwelling older adults aged ≥ 65 years from Shiki City, Japan, was surveyed by mail.

Results: We developed an instrument comprising 14 items: getting up from bed, standing up from a chair, standing up from the floor, dressing, putting on pants, eating, cleaning after toileting, washing, brushing teeth, opening a PET bottle, cutting toenails, walking inside, walking outside and going up or down four to six steps. Function scores for basic activities of daily living ranged from 14-42, with higher scores representing better function. Internal consistency was acceptable (Cronbach's alpha = 0.92). Spearman's partial correlation coefficients controlled for sex and age between the new assessment tool, and the Katz Index and Tokyo Metropolitan Institute of Gerontology Index of Competence were 0.81 (P < 0.01) and 0.63 (P < 0.01), respectively.

Conclusions: This new tool for assessment of the basic activities of daily living showed good internal consistency and validity. This assessment tool might be applicable in research and clinical practice to evaluate the basic activities of daily living of community-dwelling elderly Japanese people. Geriatr Gerontol Int 2016; 16: 1127-1137.