Functional transitions in instrumental activities of daily living among older Japanese

We observed functional transitions in instrumental activities of daily living (IADL) over one year among older Japanese and examined factors influencing the deterioration of each IADL. The sources of the study were the first and second panel studies of the Saku Longitudinal Study on Aging, which were done in 1988 and 1989. The study subjects were those participants aged 70 or older. Five IADL items--using public transportation, shopping for daily necessities, preparing meals, paying bills, and managing deposits--were measured in each survey. Deterioration of each IADL item was examined in relation to demographic characteristics such as age, sex, occupational status, living arrangements, and educational status. Of the effective baseline cohort (n = 5,559), 4,892 responded in the second survey (response rate 88%). Over 80% of the respondents who were initially independent in each IADL item remained independent in the second survey. Multiple logistic regression analyses revealed that greater age, having no occupation, and living with children at the baseline were associated with deterioration in each item of IADL. Lower educational status was associated with deterioration in each item of IADL except preparing meals. This study indicates that being engaged in work, living separately from children, and having higher educational status are strongly correlated with remaining independent in IADL for older people aged 70 or older.