Statistical methods
Component analysis and cluster analysis were performed following the
first study (12). The optimal number of clusters was based on the scree
plot, and additional for visualization a “cluspot” was drawn, plotting
subjects in two dimensions after multidimensional scaling. The variables
SAE, TNFα, IL-17, and IFNɣ, were omitted from the cluster analysis
because they were not or barely detected in the samples. We calculated
differences between patients and controls and clusters and controls
using the Mann-Whitney U test. Between-cluster differences of all
parameters were tested by using the Kruskal-Wallis test with multiple
group-comparisons. Overall, the p-values of ≤0.05 were set to be
significant.