Spatial equity in healthcare accessibility for ageing populations: an enhanced two-step floating catchment area analysis in Antalya, Türkiye

Conventional spatial accessibility metrics treat the population aged 65 years and over as homogeneous, despite well-documented declines in mobility across age sub-groups that may conceal disadvantage affecting the oldest-old. This cross-sectional ecological study quantified age-stratified inequality in healthcare accessibility across the 19 districts of Antalya province, Turkey. An age-stratified, topographically-adjusted enhanced two-step floating catchment area (AT-E2SFCA) method was developed, incorporating age-specific catchment parameters for sub-groups aged 65-74, 75-84 and 85 years and over; decoupled sub-models for acute (hospital) and preventive (primary care) services; and a topographic correction of effective travel distance. Data on 44 hospitals, 295 family health centres, 17 dialysis centres, 8 oncology centres and 920 pharmacies were obtained from official registries. Inequality was assessed using Gini coefficients, global Moran's I and Local Indicators of Spatial Association (LISA); sensitivity analyses addressed both catchment parameters and the topographic correction. Aggregate measures for those aged 65 and over underestimated inequality affecting the oldest-old by 34% for acute care and 49% for preventive care. The acute Gini coefficient rose from 0.262 (aged 65-74) to 0.362 (aged 85 and over), approaching severe inequality, whereas the aggregate composite (0.271) remained moderate. Acute and preventive disadvantage patterns were partially independent. LISA identified a high-accessibility urban core and peripheral low-access districts. A 150-bed hospital scenario was equity-neutral and locally beneficial, whereas a 250-bed expansion mildly worsened inequality by concentrating capacity. Age-disaggregated, service-decoupled accessibility metrics are essential for equity-focused geriatric health planning; strategic facility siting, rather than undifferentiated capacity expansion, drives equity gains.