This cluster nonrandomized controlled trial examined the effectiveness of a 2-year community-wide intervention (CWI) on population-level frailty and functional health among older adults. We allocated 18 districts in Ota City, Tokyo, Japan, to intervention (3 districts, A-C) and control (15 districts) groups. Of the 15,500 stratified randomly sampled residents aged 65-84 years, 11,701 (6009 in intervention and 5692 in control groups) gave valid responses to the baseline survey and were followed for 2 years. Using participatory action research framework, we developed an evidence-based CWI to promote frailty prevention. The outcomes were changes in frailty (primary), functional health (secondary, i.e., physical, nutritional, and psychosocial variables), and awareness. Primary analyses showed no significant group by time interactions in frailty prevalence (difference in multivariate-adjusted change between groups, 1.8 percentage points [PP] [95% CI, -0.1, 3.6]). Although changes in functional health were similar between groups, prespecified subgroup analyses showed a benefit for ≥150 min/week of walking (3.9 PP [1.9-5.8]) in district A, and for exercise ≥1 time/week (2.1 PP [0.1-4.0]), Motor Fitness Scale (0.10 points [0.01-0.20]), Dietary Variety Score (DVS) (0.10 points [0.01-0.18]), DVS of ≥7 (2.0 PP [0.01-4.1]), and going outdoors ≥1 time/day (2.1 PP [0.1-4.1]) in district C. Awareness of our CWI was significantly higher in the intervention group (multivariate-adjusted difference between groups, 5.8 PP [3.9-7.8]). This CWI increased awareness in intervention group and improved population-level functional health in intervention subgroups in the short term but was not effective for population-level frailty prevention at 2 years. Trial registration: UMIN-CTR (UMIN000026515).
Keywords: Action research; Community-wide intervention; Frailty; Nutrition; Older adults; Physical activity; Social participation.
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