Bidirectional association between edentulism and sarcopenia in Chinese middle-aged and older adults: a nationally representative longitudinal cohort study.

BACKGROUND

Edentulism and sarcopenia are two prevalent ageing-related conditions, yet longitudinal evidence clarifying their bidirectional relationship remains limited. We investigated the reciprocal associations between edentulism and sarcopenia among Chinese middle-aged and older adults, and further examined potential age-dependent effects.

METHODS

We used data from the nationally representative China Health and Retirement Longitudinal Study (CHARLS). Two longitudinal analytic cohorts were constructed: Cohort 1 included participants without sarcopenia at baseline (2011; n = 6,746) to evaluate whether edentulism predicts incident sarcopenia by 2015; Cohort 2 included participants without edentulism at baseline (2011; n = 7,193) to evaluate whether sarcopenia predicts incident edentulism by 2018. Sarcopenia status was classified using the 2019 Asian Working Group for Sarcopenia (AWGS) criteria based on handgrip strength, estimated appendicular skeletal muscle mass, and the five-times chair-stand test; severity was categorized as possible, confirmed, and severe. Edentulism was self-reported ("Have you lost all of your teeth?"). Multivariable logistic regression and ordinal logistic regression were applied with hierarchical adjustment for sociodemographic, health, and lifestyle covariates. Age × exposure interaction was tested, and the Johnson-Neyman technique was used to identify regions of significance.

RESULTS

In Cohort 1, 390 participants (5.8%) developed sarcopenia during follow-up; cumulative incidence was higher among edentulous than non-edentulous participants (7.5% vs. 3.8%). In fully adjusted models, edentulism was associated with higher odds of incident sarcopenia (OR 2.13, 95% CI 1.35-3.37) and greater sarcopenia severity (ordinal OR 2.07, 95% CI 1.30-3.28). A significant age interaction was observed: the edentulism-sarcopenia association was statistically significant only below 64.05 years. In Cohort 2, 453 participants (6.3%) developed edentulism; incidence increased with baseline sarcopenia severity (5.2% in no sarcopenia to 14.8% in severe sarcopenia). After full adjustment, confirmed sarcopenia (OR 1.69, 95% CI 1.24-2.30) and severe sarcopenia (OR 1.85, 95% CI 1.22-2.82) predicted incident edentulism, whereas possible sarcopenia did not.

CONCLUSIONS

This nationally representative study identified a robust bidirectional relationship between edentulism and sarcopenia in middle-aged and older Chinese adults. Edentulism was associated with an increased risk of developing sarcopenia, while confirmed and severe sarcopenia were predictive of incident edentulism. Age played a critical role in the edentulism-sarcopenia relationship, with a key threshold at 64.05 years, suggesting an earlier window for risk identification and prevention and supporting integrated "oral-muscle" screening strategies in primary care and community settings.