Global greenness in relation to reducing the burden of cardiovascular diseases: ischemic heart disease and stroke

This ecological study aimed to identify the association between greenness and cardiovascular diseases in terms of ischemic heart disease (IHD) and stroke in 183 countries worldwide. The country-level disability-adjusted life year (DALY) database provided by the WHO was used to represent the health burden due to IHD and stroke for the study countries. Normalized Difference Vegetation Index (NDVI - MOD13A3) was assessed to estimate the greenness in each country. After considering potential covariates, the generalized linear mixed model penalized quasi-likelihood coupled with a sensitivity test was applied to identify the greenness in relation to DALY loss due to IHD and stroke. Stratified analysis was then conducted to determine the effects of greenness among the different levels of gender, age, and economic status. A consistently significant negative association was found between greenness and both IHD and stroke; the NDVI coefficients of the main model were -11.245 (95% CI: -16.770, -5.720) and -4.387 (95% CI:-7.926, -0.085), respectively, in the DALY changes based on the increase of NDVI from 0 to 1. The stratified analysis recognized these effects in both females and males. Negative associations between greenness and IHD as well as stroke were also found in various age groups and were confirmed as significant in low and middle-income countries.