Edentulism and functional disability in older adults: A longitudinal and cross-national study in England, the United States, and India

Edentulism may contribute to functional disability in older adults, yet cross-national evidence combining multiple analytic strategies and mechanistic assessment remains limited. This study examined the association between edentulism and disability in activities of daily living (ADL) and instrumental activities of daily living (IADL) across England, the United States, and India. We analyzed harmonized data from the English Longitudinal Study of Ageing (ELSA; n = 9,102), the Health and Retirement Study (HRS; n = 22,156), and the Longitudinal Ageing Study in India (LASI; n = 31,816) for adults aged 60 years or older. Cross-sectional associations were estimated using inverse probability weighting (IPW) and augmented IPW. Longitudinal Cox proportional hazards models were applied in ELSA and HRS. Mediation through grip strength, body mass index (BMI), and depressive symptoms was assessed with counterfactual causal mediation analysis on the risk-difference scale. Edentulism was associated with higher odds of ADL (pooled odds ratio 1.30, 95% confidence interval 1.20-1.42) and IADL disability (1.27, 1.11-1.45). Longitudinal analyses confirmed elevated hazard ratios for incident ADL (1.19, 1.09-1.30) and IADL disability (1.30, 1.19-1.43). Grip strength accounted for the largest proportion mediated (approximately 50% in ELSA and HRS, and 5-14% in LASI); BMI and depressive symptoms showed little mediation. In LASI, denture use among edentulous participants was associated with lower disability odds. Edentulism was consistently associated with functional disability across three countries, with grip strength partially accounting for this association, although the cross-sectional design precludes establishing temporality. Oral rehabilitation may partly buffer this risk and merits further prospective investigation.