Mean IL-6 serum concentrations at hospital admission were reported in 17 studies, with a difference between the means of 24.05 pg/ml greater in patients who developed delirium than in those who did not (8, 14, 17, 20, 21, 23, 25, 31, 37, 39, 47, 48, 51, 54, 57, 58, 60). This evidence concerns the gene IL6 and delirium.