Predictive Validity of the Classification Schema for Functional Mobility Tests in Instrumental Activities of Daily Living Decline Among Older Adults

Abstract

Shimada H, Sawyer P, Harada K, Kaneya S, Nihei K, Asakawa Y, Yoshii C, Hagiwara A, Furuna T, Ishizaki T. Predictive validity of the classification schema for functional mobility tests in instrumental activities of daily living decline among older adults. Objective To determine predictive validity for cut points of the Timed Up & Go (TUG) test and life-space assessment (LSA) on decline in instrumental activities of daily living (IADLs) among older adults. Design Cross-sectional and 1-year follow-up study. Setting Preventive health care services. Participants In a cross-sectional study, 2404 older adults (65–100y) were recruited to determine cut points for the TUG and LSA for IADLs limitation. For longitudinal analysis, 436 older adults (65–100y) were followed over 1 year to explore the validity of a classification model using the cut points to predict incident IADLs decline. Interventions Not applicable. Main Outcome Measures The TUG, LSA, and Tokyo Metropolitan Institute of Gerontology index of IADLs measurement. Results The cut points associated with IADLs limitations for the TUG and LSA were 12 seconds and 56 points, respectively. Participants were classified into fast/high (most able; TUG <12 and LSA >56), fast/low, slow/high, and slow/low (vulnerable; TUG ≥12 and LSA ≤56) groups; there were 813 (34%), 385 (16%), 246 (10%), and 960 (40%) participants in each group, respectively. The proportions of participants with IADLs limitation in the most able, fast/low, slow/high, and vulnerable groups were 19%, 64%, 61%, and 89%, respectively. The vulnerable group included significantly more participants with IADLs limitation than any other group ( P<.001). Compared with a most able group, the odds ratios of IADLs decline for the fast/low and vulnerable groups were 2.52 (95% confidence interval 1.15–5.53, P<.05) and 2.87 (95% confidence interval 1.38–5.96, P<.01), respectively. Conclusions The combination of TUG and LSA identifies persons with future IADLs decline and has the potential to be used by community health care services to target individualized interventions.