Longitudinal changes in oral function and their associations with frailty status and out-of-home activity in community-dwelling older adults.

OBJECTIVE: This study aimed to characterize longitudinal changes in oral function among community-dwelling older adults and examine their associations with frailty and functional changes. METHODS: This longitudinal cohort study included 413 adults aged ≥65 years in rural Japan. Oral function, physical performance, frailty assessed using the Kihon Checklist (KCL), higher-level functional capacity assessed using the Japan Science and Technology Agency Index of Competence (JST-IC), and frequency of going out were evaluated at baseline and follow-up. Mean changes with 95% CIs and Cohen's dz were reported. Multivariable logistic regression examined factors associated with frailty worsening, adjusting for follow-up duration. Secondary linear regression analyses were exploratory and used false discovery rate correction. RESULTS: Over a mean follow-up of 3.25 years, remaining teeth, occlusal force, and maximum tongue pressure decreased significantly, although mean changes and standardized effect sizes were modest. KCL total scores increased, frailty categories shifted toward worse status, and 21.3% of participants experienced frailty worsening. The proportion reporting decreased frequency of going out increased from 9.5% to 31.6%. Greater occlusal force decline was associated with higher odds of frailty worsening (OR 1.173 per 10-kgf decline). In exploratory analyses, older age was associated with greater decline in remaining teeth, while greater KCL score increase and longer follow-up duration were associated with greater occlusal force decline after false discovery rate correction. CONCLUSIONS: Longitudinal deterioration was observed across oral function, frailty status, and out-of-home activity. The observed association suggests that occlusal force decline may occur in parallel with frailty progression in community-dwelling older adults.