EPA Scientists Find Association Between Air Pollution and Hospitalization Rates Among Heart Failure Patients
Published July 13, 2021
Heart failure is a leading cause of death in the U.S. Heart failure also poses a significant financial burden on the U.S. population due to the costs of healthcare, medication, and missed workdays for patients. In 2012, heart failure cost a total of $30.7 billion, and according to the Center for Disease Control and Prevention, this cost is expected to increase by 127 percent to $69.8 billion by 2030.
Air pollution is a major contributing factor to hospitalizations, particularly among people with cardiovascular diseases, like heart failure. Air pollution impacts have the potential to increase as the population ages and pollution from sources like wildfires grows more prevalent. Airborne particulate matter, especially fine particulate matter that is less than 2.5 microns in diameter (PM2.5), poses a substantial threat to vulnerable populations, like older adults and people with heart disease, but the effects of PM2.5 in people with underlying heart conditions are difficult to study.
EPA scientists, including computational biologist Cavin Ward-Caviness, Ph.D., conducted a study that examined the relationship between air pollution and hospitalization rates among heart failure patients. The study, published in the Journal of the American Heart Association, used a combination of electronic health records, air pollution exposure data, and rigorous statistical methods to establish an association between exposure to particulate matter and hospitalization and readmissions among heart failure patients.
To gather electronic health records and exposure data, Ward-Caviness and colleagues used EPA Clinical and Archived Records Research for Environmental Studies (CARES). This resource includes health records from the University of North Carolina Healthcare System, which were linked with a highly accurate statistical model that used satellite and ground-based measurements to estimate PM2.5 exposures. The study included data on over 20,000 heart failure patients who received initial diagnoses between 2004 and 2016; researchers focused on heart failure patients due to their enhanced environmental health risks compared to the general population. Additionally, they chose hospital visits and 30-day hospital readmission rates as markers of deteriorating health.
As Ward-Caviness explains, “Electronic health records present a great means by which to capture this unique patient population, and we were able to go far beyond previous studies by observing 30-day readmissions, which are significant to the patient and to healthcare systems that are often graded according to readmission rates.”
Researchers discovered a 14.2 percent increase in 30-day hospital readmissions and a 9.3 percent increase in total hospital visits associated with a one microgram per cubic meter increase in annual average PM2.5 (about a 10% increase over the mean concentrations in the study area), both significant findings. These results align with those of several previous studies, including a study of the southeastern U.S. using Medicare beneficiary data, highlighting the potential generalizability of this study’s methods.
Ward-Caviness remarks on the power of these results, “We employed methods that allowed us not only to estimate the association, but to understand the causal effects, which is often quite difficult to accomplish in an observational study.”
Additionally, researchers found differential associations across age, race, and gender. Among those with elevated associations were women and those diagnosed with heart failure before age 65. Black patients consistently presented the strongest associations, showing a 40 percent higher association between PM2.5 exposure and hospital visits compared to white patients, and an even greater disparity for 30-day readmissions. While differences across age may indicate a genetic component, the factors driving differences seen across gender are largely unknown. The substantial disparities seen among Black patients, however, may partially result from systemic issues, like disproportionate exposure and differential access to quality healthcare, due to systemic racism and the marginalization of minority races in the U.S. 2
This publication blazes the trail for better estimating effects of air particulate matter on cardiovascular health, but future research is needed to gain an understanding of overall health effects due to air pollution. Ward-Caviness encourages further use of electronic health records and exposure data to characterize the complex relationships between air pollution and exposed individuals. Furthermore, studies of other geographic locations, populations, and different pollution sources will allow researchers to evaluate these relationships and address air pollution as a central environmental health issue.
Link to paper: https://www.ahajournals.org/doi/full/10.1161/JAHA.120.019430
1. Ward-Caviness, C. K., et al. (2021). Long-term exposure to particulate air pollution is associated with 30-day readmissions and hospital visits among patients with heart failure. Journal of the American Heart Association.
- Tessum, C.W., et al. (2021). PM2.5 polluters disproportionately and systemically affect people of color in the United States. Science Advances.