Household air purifiers show cardiovascular benefits in former smokers with COPD

In patients with COPD who used to smoke, portable air cleaners may improve cardiovascular health, according to a study published in American Journal of Respiratory and Critical Care Medicine.

The study also showed that household particulate matter (PM) is associated with cardiac autonomic function.

“Ultrafine particles might be the most potent particles in terms of health consequences,” Meredith McCormack, MD, MHS, associate professor of medicine at Johns Hopkins University School of Medicine and director of the BREATHE (Bridging Research, Lung Health and the Environment) Center, said in a press release from Johns Hopkins Medicine. “These particles and other indoor air pollutants can cause systemic inflammation in susceptible patients like those with COPD. Our study shows there’s a negative impact on cardiovascular health, as well.”

In this ancillary study of the CLEAN AIR trial, McCormack and colleagues analyzed 85 adults (mean age, 65.6 years; 52.9% women; mean FEV₁, 55.2% predicted; mean pack-years, 51.8) with moderate to severe COPD who were former smokers to identify the relationship between indoor PM and heart rate variability (HRV), a measure linked to cardiovascular morbidity and mortality. Researchers also assessed the influence that household air cleaners had on HRV in this patient population.

As Healio previously reported, the CLEAN AIR Trial found that portable air cleaners improved respiratory outcomes among former smokers with COPD.

Before the 6-month study period began, researchers went into participants’ homes to take air samples of PM, with measurements of particles with a diameter less than 2.5 mu (PM_2.5) or 10 mu (PM₁₀) and coarse PM (PM2_.5-10). Researchers then randomly assigned participants either two portable air cleaners with HEPA and carbon filters (n = 46) or two placebo filters (n = 39).

Five times within the study period, participants wore heart rate monitors for 24 hours while researchers simultaneously assessed their indoor PM over 1-week monitoring periods. Researchers used these data for both an overall measurement of HRV, calculated as the standard deviation of normal-to-normal intervals (SDNN), and a reflection of parasympathetic activity, calculated as the root-mean square of successive differences between normal-to-normal intervals (RMSSD).

Overall, researchers evaluated 317 HRV measurements from the 85 participants.

In evaluating indoor air pollution, researchers found twofold higher PM_2.5 was linked to a 2.92% (95% CI, 0.99-4.81) decrease in SDNN, a 4.44% (95% CI, 1.44-7.35) decrease in RMSSD, and, regarding frequency domains of HRV, a 6.22% (95% CI, 2.34-9.94) decrease in high frequency (HF) power and a 7.11% (95% CI, 3.36-10.71) decrease in low frequency (LF) power.

Researchers also observed an association between elevated PM₁₀ and HRV, but not with PM_2.5-10 and HRV measures.

A twofold increase in PM_2.5 also showed more pronounced effects among participants categorized as obese, with a 4.51% (95% CI, 2.22-6.75) decrease in SDNN compared with a 1.3% (95% CI, –1.48 to 3.99) decrease among nonobese patients. HF power showed comparable results with obese participants having a decrease of 9.48% (95% CI, 3.6-15) whereas nonobese participants only had a decrease of 2.73% (95% CI, –1.44 to 8.31). Researchers also observed these associations with obesity and PM₁₀ on SDNN, RMSSD and HF power.

Comparing the two randomized groups, researchers observed a 25.2% (95% CI, 2.99-52.1) improvement in RMSSD in the active cleaner group vs. the placebo group at 6 months. HF power (31.5%; 95% CI, 2.67-68.3) and LF power (29.6%; 95% CI, 0.41-67.2) also showed improvements in the active cleaner group, but SDNN demonstrated no significant difference.

Twenty of the 46 active air cleaner participants used the devices continuously throughout the study, and researchers found that this group had a 105.7% (95% CI, 49-184) increase in RMSSD and a 102.8% (95% CI, 39.5-194.8) increase in HF power.

“In the future, air cleaners may be something to recommend to patients along with medications, but also can be part of a larger discussion about the importance of home environments,” Sarath Raju, MD, MPH, assistant professor of medicine at Johns Hopkins University School of Medicine, said in the release.

Reference:

• Household air cleaners improve heart health among individuals with COPD, researchers find. https://www.hopkinsmedicine.org/news/newsroom/news-releases/household-air-cleaners-improve-heart-health-among-individuals-with-copd-researchers-find. Published Dec. 5, 2022. Accessed Dec. 13, 2022.