Air Pollution Exposure’s Effect on Risk for Heart Failure Hospital Readmission

For individuals with underlying cardiovascular disease, a retrospective cohort study found that short-term air pollution exposure likely contributes to increasing hospital readmissions. These findings were published in the American Heart Journal.

Medical records from the University of North Carolina Healthcare System between 2004 and 2016 were reviewed. Patients (N=17,674) with heart failure (HF) were evaluated for 30-day hospital readmission on the basis of short-term exposure to air pollutants. Environmental data were sourced from the National Climatic Data Center API for patient’s addresses and daily fine particulate matter (PM_2.5) was estimated using previously published prediction models.

The entire study cohort was aged mean 68.6 years, 49.6% were men, 64.1% White, 66.8% had ischemic heart disease, 42.3% had peripheral artery disease, 33.3% had diastolic HF, and 32.8% had systolic HF.

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Overall, patients were exposed to an average of 8.8 (IQR, 6.3-12.1) mg/m³ PM_2.5. Patients were stratified by if they used beta blockers (n=13,599) or not (n=4075), and if they lived in non-urban (n=8798) or urban (n=8868) regions.

After hospital discharge, 25.0% were readmitted within 30 days and 8.1% within 1 week. The median time to admission was 122 days and the length of stay was 3 days.

Stratified by cohort, patients using beta blockers had the highest 30-day (28.1%) and 1-week (3.8%) readmission rate and those not using beta blockers had the longest length of stay (median, 4 days). The group with the highest PM_2.5 exposure was the urban cohort (mean, 9.1 μg/m³).

PM_2.5-related risk for readmission the day after discharge was increased among patients with a middle tertile of time since HF diagnosis (hazard ratio [HR], 1.12; 95% CI, 1.03-1.21), no evidence of beta blocker prescription (HR, 1.07; 95% CI, 1.01-1.14), and those living in non-urban areas (HR, 1.13; 95% CI, 1.05-1.21).

PM_2.5-related risk for readmission at 1 to 3 days after discharge was elevated overall (HR, 1.33; 95% CI, 1.18-1.51), especially among patients with no evidence of beta blocker use (HR, 1.35; 95% CI, 1.19-1.53), those in the middle tertile of time since HF diagnosis (HR, 1.60; 95% CI, 1.39-1.84), living in non-urban areas (HR, 1.43; 95% CI, 1.22-1.67), living in urban areas (HR, 1.25; 95% CI, 1.05-1.49), and with type 2 diabetes (HR, 1.41; 95% CI, 1.17-1.69).

This study may be biased as all patients were likely living in central North Carolina, so findings and the level of exposure to PM_2.5 may not be generalizable.

“The excess readmissions associated with air pollution have great economic and social costs,” the researchers wrote. “Air pollution is a modifiable risk factor, and thus the risks presented here might be mitigated by the collective actions of public health officials, health care providers, and individual patients.”

Disclosure: An author declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Wyatt LH, Weaver AM, Moyer J, et al. Short-term PM2.5 exposure and early-readmission risk: a retrospective cohort study in North Carolina heart failure patients. Am Heart J. Published online March 7, 2022. doi:10.1016/j.ahj.2022.02.015