nearly significantP = 0.072
We also performed a β‐diversity analysis, and the difference in species‐level microbial composition between the mild, moderate, and severe SpA patient groups was nearly significant ( P = 0.072 by PERMANOVA; R 2 = 0.025) (Supplementary Figure 1 , http://onlinelibrary.wiley.com/doi/10.1002/art.42289 ).