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 <2 % group. Moreover, the relative abundance of Proteobacteria increased after treatment in the patients with bEOS ≥ 2 % while a trend of decrease was observed in those with bEOS<2 %.

CONCLUSIONS Patients with eosinophilic AECOPD demonstrate better short-term clinical outcomes. The sputum microbiota in the eosinophilic and non-eosinophilic patients also respond differently to the treatment for AECOPD.