Air Pollution Associated With Increased Risk of Venous Thromboembolism
Exposure to air pollution was associated with a higher risk of developing venous thromboembolism (VTE), according to study results reported in the journal Blood.
“This study is the most deeply characterized analysis of pollution and VTE to date that we are aware of, and adds to mounting evidence that air pollution adversely impacts health,” the study’s researchers wrote in their report.
The community-based, prospective Multi-Ethnic Study of Atherosclerosis (MESA) study recruited participants from 6 communities across the US during the years of 2000 to 2002 for evaluation of the impacts of air pollution on VTE risk. The researchers characterized air pollution based on 4 factors, which included fine particulate matter of ≤2.5 micrometers in aerodynamic diameter (PM2.5), oxides of nitrogen (NOX), nitrogen dioxide (NO2), and ozone (O3). Pollution was evaluated based on a spatiotemporal model incorporating monitoring data.
The study included 6651 participants, of whom 53.0% were female. At baseline, participants had a mean age of 62.1 years (SD, 10.2). Within this population, at a median follow-up of 16.7 years, there had been a total of 248 VTE events reported, according to hospitalization discharge data obtained through 2018 on incident VTEs.
The mean PM2.5 level in this study was 13.5 μg/m3 (SD, 3.0), the mean NO2 level was 17.9 parts per billion (ppb; SD, 8.2), the mean NOX level was 36.1 ppb (SD, 19.6), and the mean O3 level was 22.2 ppb (SD, 3.7).
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Chronic exposure to air pollution, as defined by higher concentrations of PM2.5, NO2, and NOX for up to 18.5 years, was associated with increased risk of developing VTE.
The researchers evaluated relationships between VTE risk and certain thresholds of these pollutants in analyses adjusted for factors such as baseline demographics, health behaviors, and body mass index. In general, they observed greater risks of VTE with higher levels of some of these pollutants.
In an analysis, the relationship between incident VTE risk and higher PM2.5, per 3.6 μg/m3, demonstrated a hazard ratio (HR) of 1.39 (95% CI, 1.04-1.86). The relationship between incident VTE risk and a higher NO2 level, per 13.3 ppb, showed an HR of 2.74 (95% CI, 1.57-4.77).
The HR for the relationship between incident VTE and a higher NOX level, per 30.0 ppb, was 2.21 (95% CI, 1.42-3.44). However, in this analysis, incident VTE risk appeared to show no significant relationship with the O3 level per 5.8 ppb (HR, 0.78; 95% CI, 0.52-1.15).
“Chronic exposure to air pollution, as defined by higher concentrations of PM2.5, NO2, and NOX for up to 18.5 years, was associated with increased risk of developing VTE,” the researchers wrote in their report.