Abstract
INTRODUCTION: Air pollutants are increasingly recognized to affect long-term outcomes in patients with bronchiectasis. We aimed to figure out the association between air pollutants and the risk of healthcare utilization in patients with bronchiectasis. METHODS: Data for 1,029 subjects with bronchiectasis in Seoul were extracted. The air pollutants included particulate matter of 10 μm or less in diameter (PM(10)), particulate matter of 2.5 μm or less in diameter (PM(2.5)), sulfur dioxide (SO(2)), carbon monoxide (CO), ozone (O(3)), and nitrogen dioxide (NO(2)). The outcome was all-cause healthcare uses, defined as outpatient visit, emergency department visit, or hospitalization. The concentration-response curves between each air pollutant and relative risks for healthcare utilization were obtained. RESULTS: There were significant correlations between air pollutant concentrations and the risk of healthcare utilization, particularly for PM(10), NO(2), SO(2), and CO. This risk was observed even at concentrations below the recommended safe thresholds for the general population. The slopes for the association between PM(10) and NO(2) and the risk of healthcare use showed a logarithmic growth pattern, with the steepest increase up to 30 μg/m(3) and 0.030 parts per million (ppm), respectively. The curves for SO(2) and CO showed an inverted U-shaped pattern, with a peak at 0.0045 ppm and a slow upward curve, respectively. No specific trends were observed for PM(2.5) and O(3) and the risk of healthcare use. DISCUSSION: Increased concentrations of PM(10), NO(2), SO(2), and CO were associated with increased healthcare utilization in patients with bronchiectasis. For patients with bronchiectasis, there were no safety thresholds for those air pollutants, and even low levels of air pollutant exposure can negatively impact bronchiectasis outcomes.