We further measured mRNA expression of selected 13 ARDS-specific inflammatory mediators in circulating leukocytes of 200 patients with ARDS and found that ARDS patients with higher expression of IL-6, CXCL16, or IGFBP-4 had longer hospital stay (18.6 ± 4.3 vs 9.3 ± 3.2 days) and higher incidence of secondary infection (36.5 ± 6.2 vs 12.4 ± 3.6 %), respectively. This evidence concerns the gene IL6 and infection.