IL1B and delirium: Table 3 illustrates the concentrations of biomarkers detected in serum. Due to the smaller numbers in this exploratory substudy, delirium was classed as either present at any time or absent. IL-1β was found at concentrations above the LoD in 26% (6/23) of samples, and four of these samples were from the delirious group (Pearson's chi-square 2.58 p = 0.11). No differences were seen in serum levels of IL-1β, IL-1ra or IGF-1 with delirium at any stage (Table 3).