Associations between long-term fine particulate matter exposure and mortality in heart failure patients
Background:
Environmental health risks for individuals with heart failure have been inadequately studied, as these individuals are not well represented in traditional cohort studies.
Methods:
The primary objective of this study was to examine associations between ambient fine particulate matter (PM2.5) exposure and mortality in adults with heart failure (HF). Secondary objectives were to examine if associations differed by systolic vs diastolic heart failure, age at diagnosis, sex, race/ethnicity, or pre-existing co-morbidities.
This study was hospital-based cohort of all individuals diagnosed with HF between July 1, 2004 and December 31, 2016, compiled using electronic health records. Individuals were followed from one year after initial diagnosis until death or the end of the observation period (December 31, 2016). We used Cox proportional hazards models to evaluate the association of annual average PM2.5 at the time of initial HF diagnosis with all-cause mortality, adjusted for age, race, sex, distance to the nearest air pollution monitor and socioeconomic status indicators.
Results:
Among the 23,302 HF patients who contributed at-risk person-time to this study, a 1 µg/m3 increase in annual average PM2.5 was associated with an elevated risk of all-cause cause mortality (hazard ratio = 1.13, 95% confidence interval = 1.10–1.15). As compared to people with exposures below the current national PM2.5 exposure standard (12 µg/m3) those with elevated exposures experienced 0.84 (95% confidence interval = 0.73 – 0.95) years of life lost over a five-year period. Mortality associations were observed below the 12 µg/m3 PM2.5 national standard, and even after restricting to exposures below the current PM2.5 standard, substantial years of life lost (0.54 y (95% confidence interval = 0.40 – 0.69)) were associated with exposures above the median (10.1 µg/m3) as compared to below median exposures.
Conclusions:
Residential exposure to elevated concentrations of PM2.5 is a significant mortality risk factor for HF patients, particularly those diagnosed with diastolic HF. Elevated PM2.5 exposures result in substantial years of life lost even at concentrations below current national standards and mortality risks appear to differ by heart failure subtypes.