Association between Residential Green Space and Healthcare Utilization

Abstract

BACKGROUND AND AIMS Prior studies have shown greenness to be associated with beneficial health outcomes. We sought to determine if residential greenness correlated with healthcare utilization within an integrated health delivery system. METHODS We linked 5,189,303 members of Kaiser Permanente Northern California (KPNC) to Normalized Differentiated Vegetation Index (NDVI) values from Landsat satellite data (30m x 30m resolution) in 250, 500, and 1000 m radial buffers around each member's home. Healthcare utilization data for inpatient, outpatient, and emergency room visits were obtained by accessing data from the KPNC electronic health record. Using generalized estimating equations that adjusted for demographic, socioeconomic and other environmental factors, we regressed green space (in deciles) on healthcare utilization across the 2013 and 2017 study period. Adjustments were made for area sociodemographic and socioeconomic factors, and population and housing density. RESULTS We observed a significant trend across the decile range between higher levels of residential greenness and lower utilization of inpatient services (p<0.01) and emergency room visits (p<0.01). For outpatient visits, we observed a U-shaped curve where residing in middle of the NDVI range for this population was associated with greater outpatient visits than either the highest or lowest green space areas. Sensitivity analyses, including using various buffer sizes and tree canopy cover, an alternative measure of green space, yielded consistent findings. CONCLUSION Residing in an area with greater greenspace relative to low levels of greenspace was associated with greater in-patient and emergency room utilization. Residential greening can have a significant healthcare impact as measured by healthcare utilization. Keywords: green space, green cover, healthcare utilization, healthcare services