To carry out a univariate logistic regression analysis, postoperative delirium was set as the dependent variable, and the independent variables consisted of 14 factors including preoperative albumin, preoperative hemoglobin, age, gender, blood type, type of surgery, anesthesia, preoperative hospitalization, preoperative comorbidities, postoperative electrolyte disorders, blood loss, operation time, postoperative ICU care and blood transfusion (Table 3). Here, ALB is linked to Abnormal blood ion concentration.