In the present study, it was observed that 50% of patients who developed postoperative delirium and only 27% of patients without delirium had procalcitonin above the reference range prior to surgery and according to the multivariate logistic regression analysis, preoperative PCT significantly increased the risk of postoperative delirium with an odds ratio of 3.05 (p = 0.048). Here, CALCA is linked to delirium.