The variables with significant predictive value for postoperative delirium were given the weighted scores according to the relative value of the OR in multivariate logistic regression analysis: age > 75 years, history of stroke, preoperative Hb ≤ 100 g/L, preoperative PaO2 ≤ 60 mmHg, and time between admission to surgery > 3 days were weighted as 1 point, 3 points, 1 point, 2 points, and 1 point, respectively. The gene discussed is GSTM1; the disease is delirium.