Statistical analysis
Statistical analyses and figure constructions were conducted using the SPSS PASW v23 (IBM SPSS Inc., Chicago, IL), R platform v4.0.2 (R Foundation, Vienna, Austria), GraphPad Prism v5.01 (GraphPad Software Inc., San Diego, CA, USA) and MedCalc v19.0.4 (MedCalc Software Bvba, Ostend, Belgium) software. Quantitative variables are presented as mean ± standard deviation (SD), and the normal distribution of quantitative variables was assessed by the Shapiro-Wilk test. The t-test was used for comparisons of the demographic and clinical parameters between groups, depending on the homogeneity of variance. The comparisons of GM diversities between groups were assessed using the Wilcoxon rank-sum test. The top 10 GM taxa in each level (phylum, class, order, family, genus and species) sorted by higher relative abundances were identified, and the significant differences between groups were assessed using the Wilcoxon rank-sum test. The “PerformanceAnalytics” package in R was utilized for Spearman’s correlation analysis between any two demographic or clinical parameters of the subjects. In addition, Spearman’s correlation test was used to analyze the correlations between GM composition/KEGG functions and BP levels. A 