OBJECTIVE: This study assessed whether physical function can indicate a risk of decline in higher-level functional capacity.
METHODS: Data were derived from the National Institute for Longevity Sciences-Longitudinal Study of Aging. Subjects comprised 466 men and 495 women aged 40-79 years at baseline (1997-2000), whose total score for the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) at baseline was ≥11 and who participated in the follow-up survey. Baseline physical function examination included grip strength, comfortable gait speed, and sway area with eyes open. A decline in higher-level functional capacity was defined as a ≥2-point decrease in the TMIG-IC score after 14 years. The odds ratios (OR) and 95% confidence intervals (CI) for decline in the TMIG-IC score for 14 years according to a 1-standard deviation (SD) increase in physical function measurements at baseline were estimated.
RESULTS: Subjects with decreased TMIG-IC scores included 78 (16.7%) men and 80 (16.2%) women. In women, the multivariate-adjusted OR (95% CI) for a TMIG-IC score decrease with a 1-SD increase in comfortable gait speed was 0.68 (0.50-0.92; p=0.013), and that with a 1-SD increase in sway area with eyes open was 1.49 (1.17-1.90; p=0.001). Grip strength was not associated with TMIG-IC score decline. None of the physical performance measures affected TMIG-IC score declines in men.
CONCLUSION: These results suggest that gait speed decreases and sway area increases might predict a risk of decline in higher-level functional capacity among middle-aged and elderly women.