Effect of preoperative transcranial direct current stimulation on postoperative delirium in elderly patients following laparoscopic surgery

Table 1 Baseline characteristics of study participants by treatment group, n (%)

Characteristics	Sham-tDCS (n = 101)	Active-tDCS (n = 100)	P value
Sex			0.332
Male	74 (73.3)	67 (67.0)
Female	27 (26.7)	33 (33.0)
Age (year), median (IQR)	72 (69-76)	72 (69-75)	0.877
BMI (kg/m2), mean ± SD	22.79 ± 2.67	22.43 ± 2.52	0.332
ASA score (%)			0.472
II	81 (80.2)	76 (76.0)
III	20 (19.8)	24 (24.0)
History of smoking	36 (35.6)	40 (40.0)	0.524
History of anesthesia	33 (32.7)	34 (34.0)	0.842
MMSE score, median (IQR)	26 (25-28)	26 (25-28)	0.144
Hemoglobin (g/L), median (IQR)	125 (111.5-139)	123 (115.5-132)	0.680
Albumin (g/L), median (IQR)	39.14 (3.64)	39.25 (3.52)	0.827
Self-Rating Depression Scale, median (IQR)	28 (26-29)	28 (26.25-30)	0.353
Self-Rating Anxiety Scale, median (IQR)	28 (27-30)	28.5 (27-30.75)	0.104
Athens Insomnia Scale, median (IQR)	1 (1-2)	1 (1-2.75)	0.797
Age-adjusted Charlson Comorbidity Index, median (IQR)	3 (3-4)	3 (2-3)	0.327
Education level			0.657
Illiteracy	17 (16.8)	21 (21.0)
Elementary school	45 (44.6)	43 (43.0)
Middle school	28 (27.7)	28 (28.0)
High school	10 (9.9)	7 (7.0)
College graduate	1 (1.0)	1 (1.0)
Frailty			0.204
Robust	46 (45.5)	58 (58.0)
Prefrail	38 (37.6)	30 (30.0)
Frail	17 (16.8)	12 (12.0)
Comorbidities			0.728
Hypertension	40 (39.6)	44 (44.0)
Diabetes	24 (23.8)	19 (19.0)
Stroke	24(23.8)	22 (22.0)
Coronary heart disease	4 (4.0)	5 (5.0)
Type of operation			0.867
Stomach	44 (43.6)	44 (44.0)
Rectum	23 (22.8)	28 (28.0)
Colon	15 (14.9)	11 (11.0)
Liver	13 (12.9)	11 (11.0)
Pancreaticoduodenum	6 (5.9)	6 (6.0)

tDCS: Transcranial direct current stimulation; IQR: Interquartile range; BMI: Body mass index; MMSE: Mini-Mental State Examination; ASA: American Society of Anesthesiologists.