Neighborhood Poverty and Coronary Heart Disease Mortality in Washington State (CSTE Health Disparities Pilot Project)

BACKGROUND: Research consistently notes poorer health among people of lower compared to higher socioeconomic status (SES). Documenting this relationship using population-based data is challenging, because datasets often lack information on SES. This study assessed coronary heart disease (CHD) mortality in Washington State using an area-based measure of poverty. We also used the Washington Behavioral Risk Factor Surveillance System (WA-BRFSS) to see if differences in CHD risk factors by annual household income mirrored area-based CHD mortality findings.

METHODS: We used 2000 U.S. Census and 2006–2010 American Community Survey to classify census tracts by percent living below the federal poverty limit; geocoded residential address, age, sex, and cause of death from death certificates; and census-based population counts to develop age-adjusted CHD mortality rates by quartile of percent in poverty (<5%, 5.0%–9.9%, 10%–19.9%, ≥20%) for 2000–2002 combined and for 2010. We used 2000–2010 WA-BRFSS to assess relationships between annual household income and several CHD risk factors.

RESULTS: For both time periods, age-adjusted CHD mortality rates increased as percent in poverty increased: from 134/100,000 in tracts with <5% in poverty to 180/100,000 in tracts with ≥20% in poverty in 2000–2002; from 85/100,000 to 146/100,000 in 2010. Between 2000–2002 and 2010, mortality rates decreased for each poverty quartile, but decreases were smallest in the highest poverty census tracts. Compared with rates in tracts with <5% in poverty, from 2000–2002 to 2010 the disparity in CHD age-adjusted mortality rates decreased in tracts with 5.0%–9.9% in poverty, stayed the same in tracts with 10.0%–19.9% in poverty, and increased in tracts with ≥20% in poverty. We noted a similar pattern of increased disparity due to less rapid decrease in smoking for adults in households with incomes <$25,000 compared with adults with incomes ≥$75,000. This pattern was not apparent for obesity, hypertension, cholesterol screening, or having a personal healthcare provider.

CONCLUSIONS: Living in neighborhoods with high proportions of people in poverty is associated with increased risk of CHD mortality; disparities are increasing for those in areas of highest compared to lowest proportions in poverty. Increased disparity in smoking might account for some of the increased CHD mortality disparity, but we did not note increased disparities for other important risk factors. Reasons for increased disparities in CHD mortality need elucidation so that those living in areas of high poverty can receive equal benefit from advances in prevention of CHD mortality.