Comparative analysis of clinical outcomes and short-term treatment response of sputum microbiome between eosinophilic and non-eosinophilic COPD acute exacerbation

BACKGROUND: Eosinophilic AECOPD is a specific phenotype; however, the clinical outcomes and the short-term changes in sputum microbiome remain unclear. METHODS: We retrospectively included AECOPD patients admitted to National Cheng Kung Universal Hospital from January 2013 to December 2022. The primary outcome was respiratory failure rate. In addition, self-expectorated sputum was prospectively collected on days 1 and 5 of hospitalization between June 2020 and May 2021, and 16S rRNA gene segments (V3-V4) were amplified for sputum microbiome identification. Eosinophilic AECOPD were defined as blood eosinophils (bEOS) exceeding 2 % at admission. RESULTS: From the analysis of 202 AECOPD hospitalizations, patients with bEOS ≥2 % had shorter hospital stays and respiratory failure days (β-coefficient: 2.98 and -3.86, P < 0.001 and = 0.049, respectively), a lower risk of respiratory failure and intensive care unit admission (odds ratio: 0.29 and 0.35, P = 0.007 and = 0.029, respectively). In a sub-cohort of 30 AECOPD patients undergoing sputum microbiome analysis, 12 had bEOS ≥2 %, a significant decrease in Shannon diversity at the phylum level after 5 days of treatment was observed only in the bEOS