Association between masticatory performance changes and functional disability and mortality risk in older adults: a retrospective cohort study

The effects of masticatory performance changes on health outcomes remain unclear. Therefore, we examined the association between changes in objective masticatory performance and the incidence of functional disability and death. This cohort study analyzed data from individuals aged ≥75 years in Shimane, Japan, who underwent two oral health check-ups between April 1, 2016, and March 31, 2022 under Japan's Long-Term Care Insurance system. Masticatory performance was assessed using a standardized gummy jelly test, and participants were classified into high- or low-performance groups at each time point. The change groups were high-high, low-high, high-low, and low-low. We ascertained functional disability and mortality after the second assessment and estimated hazard ratios (HRs) and 95% confidence intervals (CI) using inverse probability weighting with propensity scores from all covariates, with doubly robust estimation for robustness. Of 4,410 participants, 2,000 (45.35%) were men and 2,410 (54.65%) were women. The median age was 79 years (interquartile range [IQR] 78-82) with a median follow-up of 31 months (IQR 16-42). Compared with the high-high group, HRs for functional disability or mortality were 1.75 (95% CI: 1.19-2.59) for the high-low group and 1.86 (95% CI: 1.35-2.55) for the low-low group, both statistically significant, while the low-high group showed a non-significant elevation in risk (HR 1.48, 95% CI: 0.95-2.32). The findings suggest that maintaining high masticatory performance throughout later life may be more important than later recovery, and support the integration of objective oral assessments into routine geriatric care to help extend healthy life expectancy.