Long-term air pollution exposure may elevate risk for CV mortality in patients with COPD

New data suggest that long-term exposure to fine particulate matter is associated with increased risk for cardiovascular mortality among adults with COPD.

“Air pollution, especially fine particulate matter less than 2.5 m in diameter (PM_2.5), is a modifiable risk factor related to both COPD and CVD,” Stacey E. Alexeeff, PhD, research scientist and biostatistician at the Kaiser Permanente Northern California Division of Research in Oakland, California, and colleagues wrote in the American Journal of Respiratory and Critical Care Medicine. “Short-term air pollution exposure has been associated with COPD exacerbations and with CVD events. Long-term PM_2.5 exposure is associated with a larger increase in risk for cardiovascular mortality than short-term PM_2.5 exposure.”

The retrospective cohort study enrolled 169,714 adults with COPD (mean age, 60.8 years; 56.2% women) in the Kaiser Permanente Northern California health plan from 2007 to 2016. Researchers assessed electronic health record data and linked those data to 1 km modeled PM_2.5 exposure estimates.

In the cohort, 10.5% of adults had at least one CV event at follow-up. The most common CV event was CV mortality (10,169 events), followed by acute myocardial infarction (5,970 events), ischemic heart disease mortality (5,309 events), stroke (4,269 events) and cerebrovascular mortality (917 events).

The researchers found strong associations between fine particulate matter exposure and increased risk for CV mortality in a minimally adjusted model (HR = 1.27; 95% CI, 1.17-1.38). In a fully adjusted model, there was a 10 g/m³ increase in 1-year mean PM_2.5 exposure associated with elevated risk for CV mortality among adults with COPD (HR = 1.1; 95% CI, 1.01-1.2), with the strongest association observed in low-exposure analyses (HR = 1.88; 95% CI, 1.56-2.27), according to the results.

Researchers also noted significant differences between sexes (P = .007), with increased risk for CV mortality in men (HR = 1.21; 95% CI, 1.08-1.36) but not in women (HR = 0.98; 95% CI, 0.87-1.11).

There was no association between PM_2.5 exposure and acute myocardial infarction or stroke in this study.

According to the researchers, this study demonstrated evidence of increased risk for CV events at PM_2.5 exposure levels lower than the 12 g/m³ for 1-year mean exposure in current regulations, suggesting that current regulations do not sufficiently protect adults with COPD.

“This study provides clinicians with relative risk estimates for PM_2.5 exposure so that this modifiable risk factor can be considered in a clinical context in relation to other risk factors that need to be managed,” the researchers wrote.