Background: Higher-level functional capacity is crucial component for independent living in later life. We used repeated-measures analysis to identify aging trajectories in higher-level functional capacity. We then determined whether these trajectories were associated with all-cause mortality and examined differences in medical and long-term care costs between trajectories among community-dwelling older Japanese.
Methods: 2,675 adults aged 65-90 years participated in annual geriatric health assessments and biennial health monitoring surveys during the period from October 2001 through August 2011. The average number of follow-up assessments was 4.0, and the total number of observations was 10,609. Higher-level functional capacity, which correspond to the fourth and fifth sublevels of Lawton's hierarchical model, was assessed with the Tokyo Metropolitan Institute of Gerontology-Index of Competence (TMIG-IC).
Results: We identified four distinct trajectory patterns (high-stable, late-onset decreasing, early-onset decreasing, and low-decreasing) on the TMIG-IC through age 65-90 years. As compared with the high-stable trajectory group, participants in the late-onset decreasing, early-onset decreasing, and low-decreasing TMIG-IC trajectory groups had adjusted hazard ratios for mortality of 1.22 (95% confidence interval: 1.01-1.47), 1.90 (1.53-2.36), and 2.87 (2.14-3.84), respectively. Participants with high-stable and late-onset decreasing higher-level functional capacity trajectories had lower mean monthly medical costs and long-term care costs. In contrast, mean total costs were higher for those with low-decreasing trajectories, after excluding the large increase in such costs at the end of life.
Conclusions: People with a low-decreasing aging trajectory in higher-level functional capacity had higher risks of death and had high monthly total costs.