Air pollution exposure linked to higher risk for adverse outcomes among patients with HF
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Key takeaways:
- Adverse outcomes associated with PM2.5 were more pronounced below the air quality standard threshold of 12 µg/m3.
- Patients younger than 75 years and Asian individuals were among those at greater risk.
Ambient air pollution was associated with an increased risk for adverse events among Medicare beneficiaries with preexisting HF, according to a study published in the Journal of the American Heart Association.
“While the epidemiological and experimental evidence clearly implicates PM2.5 in cardiovascular morbidity, critical knowledge gaps remain,” Amgad Mentias, MD, MS, clinical cardiologist at the Heart, Vascular and Thoracic Institute of Cleveland Clinic, and colleagues wrote, adding that data are limited on the risks associated with low exposure levels and among patients with preexisting HF.
To address these knowledge gaps, Mentias and colleagues conducted a retrospective cohort study investigating the associations between exposure to fine particulate matter of 2.5 µm or less (PM2.5) and adverse events in a cohort of older adults with preexisting HF throughout the U.S.
The researchers used Medicare Provider Analysis and Review inpatient files to identify 2,599,525 Medicare patients aged 65 years or older who were hospitalized with first HF from 2013 to 2020.
Additionally, the researchers used the patients’ ZIP codes to estimate their exposure to ambient PM2.5 obtained in 1x1 kilometer grids, dividing the cohort into three exposure groups: tertile 1 (5.6 ± 1.1 µg/m3), tertile 2 (7.3 ± 0.3 µg/m3) and tertile 3 (9 ± 1.3 µg/m3).
The primary outcome of the study was all-cause death. Secondary outcomes included first readmission with a primary diagnosis of HF, HF readmissions burden and burden of all-cause readmissions.
The researchers fit two models for each exposure variable. The first model adjusted for age, sex, race, rurality of ZIP code, census region and social deprivation index. The second model included model 1, along with diabetes, hypertension, CAD and obesity.
Overall, mean PM2.5 was 7.3 µg/m3.
Each interquartile range (IQR) of PM2.5 was associated with a 1.1% higher risk for death in model 1 (HR = 1.011; 95% CI, 1.008-1.013), with a similar trend observed in model 2 (HR = 1.009; 95% CI, 1.006-1.011).
After adjustments in model 2, researchers observed increased risk for all-cause death among patients living in tertile 2 (HR = 1.016; 95% CI, 1.011-1.022) and tertile 3 (HR = 1.02; 95% CI, 1.014-1.025) of exposure compared with those in tertile 1.
Patients younger than 75 years, Asian individuals, those without diabetes and those living in rural areas were at increased susceptibility for harmful effects of PM2.5 exposure, according to the researchers.
Each IQR of PM2.5 smaller than 7.3 µg/m3 was associated with a 5.1% (HR = 1.051; 95% CI, 1.043-1.06) increase in first HF hospitalization in model 1, again with similar results in model 2 (HR = 1.045; 95% CI, 1.037-1.053). When looking at the risk for first HF hospitalization in model 2, those residing in tertile 2 (HR = 1.023; 95% CI, 1.016-1.03) and tertile 3 (HR = 1.018; 95% CI, 1.01-1.025) appeared at greater risk compared with patients residing in tertile 1.
Data from model 2 showed each IQR of PM2.5 was also associated with a 3.1% (RR = 1.031; 95% CI, 1.027-1.036) increase in overall HF readmission burden and 5.2% (RR = 1.052; 95% CI, 1.048-1.056) increase in all-cause readmission burden.
“At the national and the global scale, PM2.5 exposure affects a large number of patients, particularly those living in socioeconomically disadvantaged neighborhoods,” the researchers wrote. “As such, PM2.5 exposure likely contributes to the disparities in HF outcomes noted in national studies and offers a target for interventions.”
The researchers acknowledged study limitations, including that PM2.5 exposure is a model-based estimate and prone to misclassification.
“Interventions to reduce PM2.5 at the individual and community level should be investigated to reduce HF death and morbidity,” the researchers wrote.
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