Local-Area Walkability and Socioeconomic Disparities of Cardiovascular Disease Mortality in Japan

BACKGROUND: There are spatial disparities in cardiovascular disease (CVD) mortality related to area-level socioeconomic status (SES) disadvantage, but little is known about the spatial distribution of CVD mortality according to built environment factors. We examined joint associations of neighborhood walkability attributes and SES with CVD mortality rates through linkage of Japanese national data sets. METHODS AND RESULTS: National data were used from the 1824 municipalities (of the 1880 potentially eligible municipalities) across Japan. The outcome was mortality from CVD for a 5-year period (2008-2012) for each municipality. A national index of neighborhood deprivation was used as an indicator of municipality-level SES. A national walkability index (based on population density, road density, and access to commercial areas) was calculated. Compared with higher SES municipalities, relative rates for CVD mortality were significantly higher in medium SES municipalities (relative rate, 1.05; 95% CI, 1.02-1.07) and in lower SES municipalities (relative rate, 1.09; 95% CI, 1.07-1.12). There were walkability-related gradients in CVD mortality within the high and medium SES areas, in which lower walkability was associated with higher rates of mortality; however, walkability-related CVD mortality gradients were not apparent in lower SES municipalities. CONCLUSIONS: CVD mortality rates varied not only by area-level SES but also by walkability. Those living in areas of lower walkability were at higher risk of CVD mortality, even if the areas have a higher SES. Our findings provide a novel element of the evidence base needed to inform better allocation of services and resources for CVD prevention.