GIS-Based Spatial Accessibility to Urban Resources and Healthy Aging: Environmental Exposure Assessment of Frailty, Cognition, and Polypharmacy in Older Adults

Characterizing how the built environment shapes the health of aging populations is a growing priority for environmental assessment and for the spatial decision-support tools that inform age-friendly planning. Geographic information systems (GIS) allow neighborhood resources to be treated as measurable environmental exposures for older residents. We examined whether geographic information system (GIS)-derived measures of spatial accessibility to key urban resources are associated with cognitive impairment, physical and cognitive frailty subtypes, and polypharmacy in a cross-sectional study of 317 community-dwelling adults aged ≥65 years in the city of Talca, Chile. Physical frailty was assessed with the Fried phenotype, cognitive impairment with an abbreviated Mini-Mental State Examination, and polypharmacy as the daily use of ≥5 medications. A summary Urban Quality Index (UQI), a distance-based measure of spatial accessibility to neighborhood resources, was constructed from Euclidean distances and analyzed in quartiles and as a binary indicator. Cognitive impairment (25.2%), polypharmacy (49.5%), and frailty (35.0%) were highly prevalent and frequently co-occurred. In multivariable models adjusted for age, sex, education, body mass index, and nutritional risk, low UQI was not significantly associated with any outcome. Resource-specific distance patterns should be considered exploratory. These findings suggest that residence-based, straight-line accessibility may not capture the environmental exposures most relevant to healthy aging—consistent with the uncertain geographic context problem—and that richer indicators, such as walkability, public-space quality, physical barriers, and mobility-based exposure, are needed before such indices can support environmental decision-making. Given the cross-sectional design, the results are preliminary spatial associations and do not demonstrate that environmental accessibility influences these outcomes.