Spatial health inequities among older adults in Thailand: a composite vulnerability index and relationship with local development

Abstract Background Thailand is undergoing a rapid demographic transition toward an aging society, with substantial challenges in ensuring health equity for older adults. While national-level health policies have expanded coverage and services, spatial disparities in health risks and local development remain underexplored, particularly through integrative spatial frameworks. Objective This study aimed to examine the spatial distribution of health vulnerability across Thai provinces and its spatial association with local development. Methods Data were obtained from the 2024 nationwide community-based screening program for older adults in Thailand, covering nine health risk indicators: cognitive impairment, mobility limitation, visual impairment, hearing impairment, urinary incontinence, activities of daily living limitation, oral health problems, malnutrition risk, depression risk. A composite health vulnerability index (CHVI) was constructed using principal component analysis, with the first component explaining 74.83% of total variance. Spatial clustering was assessed using Global Moran’s I and local indicators of spatial association (LISA), while bivariate LISA examined the spatial relationship between CHVI and local development, proxied by nighttime light (NTL) intensity derived from satellite imagery. Results The CHVI demonstrated strong positive loadings across all nine geriatric risk indicators. Global Moran’s I was 0.261 (p = 0.002), indicating significant spatial autocorrelation. LISA analysis revealed high–high clusters of CHVI predominantly in the Northeastern region, while NTL intensity was concentrated in the Central region. The negative bivariate Moran’s I (− 0.174, p < 0.05) indicated overall spatial dissimilarity between health vulnerability and local development. Notably, nine central provinces surrounding Bangkok exhibited high CHVI values spatially associated with lower neighboring NTL intensity. Conclusion The CHVI provides a spatially explicit measure for identifying provincial-level geriatric health risks. By examining spatial associations between health vulnerability and local development, this approach offers evidence to inform geographically targeted strategies aimed at promoting healthy aging and addressing regional inequities in Thailand.