Sex, age, BMI, cognitive status, nutritional status, CCI, ASA score, stroke, malignant disease, albumin, NT‐proBNP, creatinine, haemoglobin, anaesthesia type, type of surgery, length of hospital stay, ICU admission rate, length of ICU stay, presence of postoperative complications, severity of surgical complication, presence of postoperative delirium. Here, NPPB is linked to delirium.