Objectives: To assess individual variation in the functional capacity of community-dwelling older people who are almost independent in daily living, using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-Index of Competence).
Methods: Out of 74 elderly outpatients showing a total score of TMIG-Index of Competence above 10 points at baseline, 61 who remained stable during subsequent two months in terms of medical and social aspects were assessed for their functional capacity with the test-retest method using the TMIG-Index of Competence. We assessed individual variation between the tests of one month interval with correspondence rate.
Results: The ranges for score differences within which correspondence rates of 95% and over applied were as follows: within 1 point for the total score of the Index (95.1%), 0 point in the Instrumental Self-Maintenance subscale (IADL) (95.1%), and 1 point in the Intellectual Activity subscale (Intellectual Activity) (98.4%) and the Social Role subscale (Social Role) (98.3%).
Conclusions: The variation of 1 point for the total score of the Index, and subscales of Intellectual Activity and Social Role was regarded as a possible measurement error. In other words, variations of 2 points and over for total score, subscales of Intellectual Activity and Social Role, and variations of 1 point and over for IADL should not be ignored in screening of functional capacity among older people.