Air pollution exposure elevates risk for blood clot hospitalization
Key takeaways:
- Adults exposed to high levels of air pollution over several years exhibited higher risk for venous thromboembolism.
- Certain pollutants more than doubled the risk for blood clots.
Long-term exposure to certain air pollutants significantly increased risk for venous thromboembolism, according to results of an observational study.
Adults who had higher exposure to fine particulate matter equal to or less than 2.5 micrometers in aerodynamic diameter, oxides of nitrogen and nitrogen dioxide — all common pollutants — had a higher likelihood of developing blood clots than those who had lower exposure.
“This study supports the case for global efforts on pollution reduction to curtail pollution-related adverse health outcomes,” Pamela L. Lutsey, PhD, MPH, professor at University of Minnesota School of Public Health, told Healio. “Previously, most work on pollution had looked at respiratory disease and cardiovascular disease. What we showed in this study is that pollution also extends to venous thromboembolism.”
Background
Nearly 1 million individuals in the U.S. develop VTE each year, according to study background.
Prior research showed air pollution increased markers for blood coagulation and inflammation, both of which are associated with VTE.
“Very high levels of air pollution [such as those in a wildfire] may lead to a short-term surge in VTE cases, but what we were curious about was whether chronic air pollution exposure is a risk factor for VTE,” Lutsey said. “These pollutants are things people are exposed to in their everyday lives.”
Methods
The prospective Multi-Ethnic Study of Atherosclerosis (MESA) study assessed factors that led to plaque buildup in arteries.
Researchers enrolled 6,814 individuals classified as either Hispanic, non-Hispanic Black, non-Hispanic white or non-Hispanic Chinese between 2000 and 2002. Participants lived in one of six different communities — Chicago; New York; Baltimore; Los Angeles; St. Paul, Minnesota; and Forsyth County, North Carolina.
Researchers started the MESA Air Pollution ancillary study to determine the impact air pollution has on the development of cardiovascular disease.
They used models — which included geographical predictors, agency monitoring data and community-specific measurements — to evaluate air pollution levels every 2 weeks from 1999 to 2018.
Lutsey and colleagues included 6,651 adults (mean age, 62.1 years; standard deviation ± 10.2; 53% women; 38.4% white; 27.5% Black; 22% Hispanic) from that study in their analysis.
The association between VTE and long-term exposure to fine particulate matter equal to or less than 2.5 micrometers in aerodynamic diameter, oxides of nitrogen, nitrogen dioxide and ozone served as the primary endpoint.
Key findings
After median follow-up of 16.7 years, 248 VTE events occurred among the study population.
Individuals in the 75th percentile of exposure to fine particulate matter had a 43% greater risk for VTE than those in the 25th percentile (HR = 1.43; 95% CI, 1.08-1.91).
VTE risk also appeared elevated among adults in the 75th percentile of exposure for oxides of nitrogen (HR = 2.3; 95% CI, 1.48-3.57) and nitrogen dioxide (HR = 2.87; 95% CI, 1.64-5.01).
The associations persisted regardless of smoking status.
“I was actually surprised by how strong the associations were,” Lutsey said. “These data are absolutely incredible.”
Researchers observed no association between increased exposure to ozone and elevated VTE risk.
Future research could evaluate whether clean air policies and reductions in air pollution decreased VTE rates or coagulation and inflammation markers, Lutsey said.
“If we see that improving air quality leads to improved levels of markers of inflammation and coagulation in the blood, that suggests that policies to reduce air pollution may also have additional benefits in lowering VTE risk,” she said.
For more information:
Pamela L. Lutsey, PhD, MPH, can be reached at lutsey@umn.edu.
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