Abstract 5: Trends in Hospitalization Rates and Mortality for Acute Myocardial Infarction by Community Income Level: 1999-2013

Abstract

Background: Over the last decade, acute myocardial infarction (AMI) incidence and mortality have decreased substantially. Yet it is unknown whether these improvements were consistent across communities of different economic status and geographic regions, for which efforts to improve cardiovascular disease prevention and management may have had variable impact. Objective: To compare trends in risk-standardized AMI hospitalization and 1-year mortality rates from 1999 to 2013 between counties of low, average, and high median income, and to test the effects of income over time and across the 4 U.S. geographic regions. Methods: We performed an observational analysis comparing trends in county-level risk-standardized (age, sex, race) AMI hospitalization and 1-year mortality rates from 1999 to 2013 among Medicare beneficiaries ≥65 years, testing for effects of county-income. Counties were stratified by median income percentile using 1999 U.S. Census Bureau data, adjusted for inflation, as: low (<25th), average (25-75th) or high (>75th) income groups. Using a mixed effects model, we compared trends in AMI hospitalization and mortality rates, stratified by county income. We tested for a lagged effect among low-income counties and compared trends between the 4 U.S. regions. Results: Income was significantly associated with AMI hospitalization, but not 1-year mortality rates. In the 15-year period, AMI risk-standardized hospitalization and mortality rates declined across all three county income groups, though absolute hospitalization rates differed significantly by county income groups (Figure). Low-income county hospitalization rates consistently lagged behind high-income county rates by 4.3 (95%CI: 3.1-5.9) years. There was no difference in rate of decline by geographic region. Conclusion: In this national study of AMI trends from 1999 to 2013, Medicare beneficiaries residing in counties of all income levels achieved substantial declines in AMI hospitalization and mortality. These broad-scale declines may reflect the success of focused AMI prevention efforts or other more secular trends. Nonetheless, disparities persist with low-income counties lagging behind high-income counties - a focus for future national efforts.