Early strong predictors of decline in instrumental activities of daily living in community-dwelling older Japanese people

OBJECTIVE: Our aim is to determine the strong predictors of the onset of instrumental activities of daily living (IADL) decline in community-dwelling older people. DESIGN: A prospective cohort study with a two-year follow-up. SETTING: Kashiwa City, Chiba Prefecture, Japan and Toshima Ward, Tokyo Metropolitan, Japan. PARTICIPANTS: The data were acquired from two cohorts. The final sample comprised 1,523 community-dwelling older people aged 65–94 years (681 men, 842 women). They were individuals who were independent in IADL at baseline and participated in follow-up IADL assessments two years later. MEASUREMENTS: At baseline, comprehensive assessments were performed including: health interview, gait function, hand-grip strength, skeletal muscle mass, balance function, oral function, dietary lifestyle, cognitive function, quality of life, mental status, and social network. When the two-year follow-up was performed, IADL declines were observed in 53 out of 1,523 people. The association of each Z-transformed parameter with the occurrence of IADL decline was examined by employing a binominal logistic regression model adjusting for age, gender, body weight, body height, and medical history. An odds ratio (OR) and a 95% confidence interval were calculated and compared between different parameters. RESULTS: A decrease in walking speed and one-legged stance time, whereas an increased timed up & go test time was associated with significant ORs for the occurrence of IADL decline. CONCLUSION: Gait-related parameters appear to be the strong predictors of the onset of IADL decline in community-dwelling older people.