Green space and mortality following ischemic stroke.

ABSTRACT

BACKGROUND: Residential proximity to green space has been associated with physical and mental health benefits, but whether green space is associated with post-stroke survival has not been studied. METHODS: Patients ≥ 21 years of age admitted to the Beth Israel Deaconess Medical Center (BIDMC) between 1999 and 2008 with acute ischemic stroke were identified. Demographics, presenting symptoms, medical history and imaging results were abstracted from medical records at the time of hospitalization for stroke onset. Addresses were linked to average Normalized Difference Vegetation Index, distance to roadways with more than 10,000 cars/day, and US census block group. Deaths were identified through June 2012 using the Social Security Death Index. RESULTS: There were 929 deaths among 1645 patients with complete data (median follow up 5 years). In multivariable Cox models adjusted for indicators of medical history, demographic and socioeconomic factors, the hazard ratio for patients living in locations in the highest quartile of green space compared to the lowest quartile was 0.78 (95% Confidence Interval 0.63-0.97) (p-trend = 0.009). This association remained statistically significant after adjustment for residential proximity to a high traffic road. CONCLUSIONS: Residential proximity to green space is associated with higher survival rates after ischemic stroke in multivariable adjusted models. Further work is necessary to elucidate the underlying mechanisms for this association, and to better understand the exposure-response relationships and susceptibility factors that may contribute to higher mortality in low green space areas.