High-efficiency air cleaners decrease exacerbations and the use of rescue medication in former smokers with COPD

Reference

Hansel NN, Putcha N, Woo H, et al. Randomized clinical trial of air cleaners to improve indoor air quality and chronic obstructive pulmonary disease health: results of the CLEAN AIR study. Am J Respir Crit Care Med 2022;205(4):421-430.

Synopsis

These researchers enrolled 116 former smokers with moderate to severe COPD (FEV1/FVC ratio 70% or less, FEV1 less than 80% predicted) and who resided in homes where the indoor air particulate matter exceeded 10 mcg/m3. The authors randomized the participants (unknown if the allocation was concealed) to receive 2 active air cleaners or 2 sham air cleaners. The active cleaners had high-efficiency particulate absolute (HEPA) and carbon filters; the sham cleaners had these filters removed, so the air movement and noises were identical. The researchers evaluated the participants sequentially for 6 months. Using intention-to-treat, after 3 months, the researchers saw no effects. After 6 months, although there was no difference in overall health-related quality of life, the participants using the active air cleaners had statistically significant greater improvement in symptom scores (clinical significance unknown). Although the average number of moderate exacerbations (needing systemic steroids, antibiotics, or urgent health care visits) was 0.4 in the active air cleaner group compared with 1.25 in the sham group (relative risk 0.32; 95% CI 0.12 - 0.91), there was no difference in the rate of exacerbations requiring emergency department visits or hospitalizations. Additionally, the average frequency of the use of rescue medication was lower in the active air cleaner group than in the sham group (1.88 vs 3.51). The participants with the lowest FEV1 at baseline and those spending more time indoors with the air cleaner on more than 80% of the time had the greatest improvements.