Socioeconomic Gradients in Multidomain Functional Vulnerability Among Older Adults in Türkiye: A Nationally Representative Analysis

Background/Objectives: Preserving independence in later life is a public health priority in Türkiye’s ageing population, yet socioeconomic inequalities across functional domains and regions remain insufficiently characterized. We examined educational and income gradients across five domains of functional vulnerability among older adults and assessed regional variation. Methods: The nationally representative 2023 Türkiye Older Persons Profile Survey included 11,657 adults aged ≥ 65 years from 8754 households. Outcomes comprised dependency in activities of daily living (ADL), limitations in instrumental activities of daily living (IADL), health–mobility burden, sensory/communication burden and reported cognitive difficulty. Survey-weighted generalized estimating equation models examined education and equivalized household income simultaneously, accounting for household clustering and adjusting for sociodemographic covariates and region. All outcomes were expressed on a 0–1 scale. Log-transformed income was modelled using restricted cubic splines. Regional interactions were assessed with Holm correction. Results: Lower education and income were associated with greater vulnerability across all five domains after mutual adjustment. Compared with higher education, no completed schooling showed the largest differences for IADL limitation (adjusted mean difference [AMD] 0.216, 95% CI 0.187–0.245) and reported cognitive difficulty (AMD 0.166, 95% CI 0.146–0.186). The largest income contrast was observed for IADL limitation (AMD 0.126, 95% CI 0.102–0.150; weighted 10th versus 90th percentile). After Holm correction, regional heterogeneity remained for education and income gradients in IADL limitation and for the education gradient in health–mobility burden. Conclusions: Socioeconomic differences varied across functional domains and selected gradients differed by region. IADL limitation showed the largest absolute education- and income-related differences under the scoring approach used. The cross-sectional design precludes causal interpretation.