Particulate matter 2.5, metropolitan status, and heart failure outcomes in US counties: A nationwide ecologic analysis

The relationship between particulate matter with a diameter of 2.5 micrometers or less (PM(2.5)) and heart failure (HF) hospitalizations and mortality in the US is unclear. Prior studies are limited to studying the effects of daily PM(2.5) exposure on HF hospitalizations in specific geographic regions. Because PM(2.5) can vary by geography, this study examines the effects of annual ambient PM(2.5) exposure on HF hospitalizations and mortality at a county-level across the US. A cross-sectional analysis of county-level ambient PM(2.5) concentration, HF hospitalizations, and HF mortality across 3135 US counties nationwide was performed, adjusting for county-level demographics, socioeconomic factors, comorbidities, and healthcare-associated behaviors. There was a moderate correlation between county PM(2.5) and HF hospitalization among Medicare beneficiaries (r = 0.41) and a weak correlation between county PM(2.5) and HF mortality (r = 0.08) (p-values < 0.01). After adjustment for various county level covariates, every 1 ug/m(3) increase in annual PM(2.5) concentration was associated with an increase of 0.51 HF Hospitalizations/1,000 Medicare Beneficiaries and 0.74 HF deaths/100,000 residents (p-values < 0.05). In addition, the relationship between PM(2.5) and HF hospitalizations was similar when factoring in metropolitan status of the counties. In conclusion, increased ambient PM(2.5) concentration level was associated with increased incidence of HF hospitalizations and mortality at the county level across the US. This calls for future studies exploring policies that reduce ambient particulate matter pollution and their downstream effects on potentially improving HF outcomes.