Fig. 1

Analysis of the sputum microbiome and diversity in stable COPD. The unweighted PCA plot (a) and Chao1 index, observed OTUs, and Shannon index (b) were calculated in the LRE vs HRE groups. The unweighted PCA plot (c) and the diversity index (d) were presented in the PFT I vs PFT II groups. The box and whiskers plots show the median, 10th and 90th percentile in each group. Bonferroni-adjusted p-values < 0.05/6 = 0.0083 indicate significance. LRE low-risk exacerbator, HRE high-risk exacerbator