Background: Comparisons of greenspace between metropolitan areas generally reflect regional differences in soil characteristics and climatic zone, while greenspace differences within a metropolitan area at the postal code level avoid these regional differences. We examined local differences and trends in greenspace as determinants of local differences and trends in cardiovascular health.Methods: We calculated annual age-adjusted cardiovascular hospital admission rates (admissions per 100,000 person-years at risk, CHR) among Medicare beneficiaries aged 65 years and older for 2002-2013 across 10,097 ZIP codes (postal codes) in 123 major metropolitan core-based statistical areas (CBSA). We obtained monthly normalized difference vegetative index (NDVI) from the Terra satellite (1km grid) mapped to metropolitan ZIP code, determined the month with maximum NDVI for each metropolitan area, and finally assigned maximum-month values of NDVI for each ZIP code and year. Finally, we modeled the associations scaled to the interquartile range (IQR) both for centered means and for 12-year trends in CHR and NDVI, adjusting for CBSA and for levels and trends in adjusted gross income, proportion White and population density.Results: Across 123 major US metropolitan areas for 2002-2013, CHR had a mean of 5,903 admissions per 100,000 person-years at risk and a trend of -122 per year. An IQR increment of 0.121 in the mean NDVI was associated with a 52.4 lower CHR (95% CI 20.4, 84.3), while an IQR increment of 0.018 in the annual trend in NDVI was associated with a 6.4 per year greater decrease in CHR (95% CI 4.5, 8.3).Conclusion: Thus, after adjustment for metropolitan area characteristics and for cardiovascular risk factors, we have shown that local improvements in greenspace (NDVI) lead to local improvements in cardiovascular health among Medicare beneficiaries.This abstract does not necessarily represent the views or policies of the U.S. Environmental Protection Agency.
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