Variable importance plot of protein biomarkers measured by the random forest built from the training set. ACE indicates angiotension converting enzyme; creatine kinase MB, creatine kinase muscle-brain; IL, interleukin; MCP1, monocyte chemoattractant protein 1; MIF, macrophage migration inhibitory factor; MIP1α, macrophage inflammatory protein 1-α; PARC, pulmonary and activation-regulated chemokine