Oral Frailty as a Predictor for Weight Loss in Older Japanese: A Cohort Study

Oral frailty is a key factor in maintaining nutritional status, yet its impact on weight loss remains unclear. This study aimed to (1) evaluate the longitudinal association between oral frailty and the onset of weight loss among independent older adults and (2) explore how oral frailty components contribute to this association. Data were sourced from 2016 to 2022 of the Japan Gerontological Evaluation Study (JAGES). As a 6-y follow-up cohort study, the onset of >10% weight loss was used as the dependent variable, reflecting the significant threshold for older adults at ≥6-mo follow-up. Oral frailty was assessed as independent variables in 4 ways: (a) count score (sum of 5 components: fewer teeth, chewing difficulty, swallowing difficulty, dry mouth, and pronunciation difficulty), (b) individual 5 components, (c) a latent variable structured from 5 components, and (d) a refined latent variable incorporating additional paths from fewer teeth to chewing difficulty and pronunciation difficulty. Structural equation models (SEMs) were applied to examine the effect of oral frailty on weight loss, estimating standardized coefficients (SCs) and 95% confidence intervals (CIs). The construct validity of oral frailty was assessed using confirmatory factor analysis within the SEM framework. Model fit was evaluated using the standardized root mean squared residual (SRMR) and coefficient of determination (CD). Among 3,305 participants (47.4% women; mean age at baseline: 72.0 ± 4.9 y), 8.9% experienced >10% weight loss. Model d, which incorporated a refined latent structure of oral frailty, demonstrated the strongest association with weight loss (SC = 0.09; 95% confidence interval [CI] = 0.01; 0.16) among all models, with chewing difficulty showing the highest standardized factor loading (0.45; 95% CI = 0.35; 0.55). Model d also showed the best model fit (SRMR = 0.013; CD = 0.217), providing the high explanatory power and appropriateness of this model. Oral frailty significantly increases the risk of weight loss among independent older adults and its components have interrelationships.