Association between urban green space and the risk of cardiovascular disease: A longitudinal study in seven Korean metropolitan areas

Purpose: Few previous studies have investigated the association between urban green space and cardiovascular disease (CVD) within Asian populations. We aimed to determine the relationship between amount of green space in the residential environment and CVD within a large general Asian population in this population-based longitudinal study. Methods: The study population consisted of 351,409 participants aged over 20 years extracted from the National Health Insurance Service National Sample Cohort. Data on newly-occurred CVD events were collected from hospital admission records for the period 1 January 2006 to 31 December 2013. Cox proportional hazards regression analysis was used for determining the risk of developing CVD according to urban green space coverage (% area), adjusting for a number of relevant confounders. Results: Compared to those within the lowest quartile of green space coverage, those within the highest quartile of urban space had a reduced risk of total CVD (hazard ratio, HR 0.85, 95% confidence interval, CI 0.81–0.89), coronary heart disease (HR 0.83, 95% CI 0.78–0.89), acute myocardial infarction (HR 0.77, 95% CI 0.68–0.88), total stroke (HR 0.87, 95% CI 0.82–0.93) and ischemic stroke (HR 0.86, 95% CI 0.80–0.94), but not hemorrhagic stroke (HR 0.98, 95% CI 0.86–1.12). The risk-reducing effect of green space coverage was preserved after stratification according to sex, household income, and Charlson comorbidity index. Conclusion: Residing in urban regions with greater green space coverage may lead to a reduced risk of CVD. Urban planning intervention policies that increase urban green space coverage could help to reduce the risk of CVD.