We performed a multiplex cytokine bead assay blindly and in parallel using the Bio-plex Pro Human Cytokine assay (Bio-Rad, Hercules, CA) and Milliplex MAP Human Cytokine/Chemokine panel 1 (Millipore, Billerica, MA) according to the manufacturers’ instructions as described previously.[15 (link)] The subjects’ baseline demographic characteristics were compared using Fisher's exact test for discrete variables and the Wilcoxon test for continuous variables. The Kruskal–Wallis test followed by Dunn's multiple comparisons test was used to compare cytokine levels between groups. To rank the cytokine levels, we performed a multivariate classification algorithm termed random forest analysis (RFA),[16 ] using the R package RandomForest (http://cran.r-project.org/web/packages/randomForest/) ver. 4.6–12 software, as previously described.[17 (link)]