Objectives: We reported previously that a 10-year community intervention for disability prevention successfully extended healthy life expectancy at 70 years and decreased the enrollment rate of the Long-Term Care Insurance in Kusatsu, Gunma Prefecture, Japan. In order to clarify functional factors that contributed to healthy aging, this study examined changes in physical, nutritional, psychological and social functions in older adults who participated in annual health checkups over the period.
Methods: Data sources were participants in annual health checkups conducted from 2002 to 2012 and respondents to biannual monitoring surveys conducted from 2003 to 2011. The target population was all older adults aged 70 years and over living in Kusatsu. The average participation rate over the period was 34.7% for the annual health checkups and 95.0% for the monitoring surveys. First, we examined the representativeness of the participants in annual health checkups by comparing them with the responders to monitoring surveys in terms of their higher-level functional capacity, as measured by the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) (Analysis 1). Second, we examined changes in the physical (4 measures), nutritional (3 measures), and psychological and social (4 measures) functions of participants in annual health checkups over the period. In this analysis, we standardized the data for each year on 11 measures to a mean of 0 and a standard deviation of 1.0 using the 2002 data as the standard, and conducted statistical tests for the slopes of the linear approximate equation (intercept=0) (Analysis 2).
Results: In Analysis 1, the TMIG-IC scores for participants in the annual health checkups were significantly higher in both sexes than were those for responders to the monitoring surveys. However, there were no significant year×group interactions in the scores. The difference in scores between the two groups was small for participants in their seventies, but large for participants in their eighties or over. Analysis 2 showed that all physical functions improved significantly over the period in both sexes, and the slopes of the linear approximate equation were steeper for maximal and usual gait speeds (slope=0.050 and 0.048, respectively, in men; 0.067 and 0.060, respectively, in women) than for other measures. In women, in addition to physical function, scores on the Mini-Mental State Examination (slope=0.053), Geriatric Depression Scale (slope=0.027), and Social Roll Scale (slope=0.019) also increased significantly.
Conclusion: Although participants in annual health checkups were biased toward better functioning, the degree of the bias did not change significantly over the period. During the same period, physical function for both sexes, and psychological and social functions for women, improved significantly. It may be concluded that functional improvement in older adults contributed to the healthy longevity in Kusatsu.