During delirium there was strongest evidence for higher interleukin-6 (IL-6) (MD 21.29, 95% CI 11.78, 30.80, p < 0.00001), cortisol (MD 159.6, 95% CI 120.52, 198.68, p < 0.00001), and leukocyte count (MD 0.79, 95% CI 0.51-1.07, p < 0.000001) in delirium compared to no delirium.<h4>Discussion</h4>These results support a role for peripheral immune response and inflammation in delirium. Here, IL6 is linked to delirium.