No significant differences in age, sex, height, body weight, ASA grade, underlying diseases such as hypertension, diabetes, coronary heart disease, drinking history, smoking history, preoperative Hb, preoperative albumin, years of education, preoperative MMSE score and preoperative PSQI score were observed among two groups in Table 1 (P > 0.05). This evidence concerns the gene GSTM1 and Hypertension.