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.

Table 2 Postoperative data by treatment group, n (%)

Characteristics	Sham-tDCS (n = 101)	Active-tDCS (n = 100)	P value
Postoperative delirium	23 (22.8)	7 (7.0)	0.002
Days with delirium, median (IQR)	2 (1-2)	2 (1.25-2)	0.432
Type of delirium			0.829
Hypoactive	15	4
Hyperactive	4	1
Mixed	4	2
Self-Rating Anxiety Scale, median (IQR)	27 (24.5-28)	26 (24-27)	0.045
Self-Rating Depression Scale, median (IQR)	27 (26-29)	26 (25-28)	0.024
Numeric Rating Scale score, median (IQR)	4 (3-5)	4 (3-4)	0.243
Use of salvage analgesics	18 (17.8)	14 (14.0)	0.459
Duration of hospitalization, median (IQR), day	14 (12-18)	15 (13-18)	0.445

tDCS: Transcranial direct current stimulation; IQR: Interquartile range.

Table 3 Binary logistic regression analysis was performed to analyze the risk factors of postoperative delirium

Characteristics	Univariable analysis unadjusted OR (95%CI)	P value	Multivariable analysis adjusted OR (95%CI)	P value
Group	0.255 (0.104-0.627)	0.003	0.284 (0.111-0.727)	0.009
Age	2.889 (1.177-7.089)	0.021	1.994 (0.758-5.241)	0.162
ASA	1.665 (0.701-3.954)	0.248	-	-
MMSE	0.253 (0.098-0.650)	0.004	0.275 (0.102-0.739)	0.010
History of smoking	1.803 (0.826-3.938)	0.139	-	-
FRAIL	3.918 (1.596-9.616)	0.003	2.838 (1.091-7.382)	0.032
Hemoglobin1	1.443 (0.627-3.319)	0.388	-	-
Albumin	0.474 (0.213-1.057)	0.068	0.599 (0.251-1.430)	0.248
AIS	2.000 (0.726-5.512)	0.180	-	-
Duration of surgery	1.686 (0.709-4.009)	0.237	-	-

¹Normal hemoglobin values are 120-160 g/L for adult men and 110-150 g/L for adult women.

The multivariable section in the model only used variables with P < 0.100. Specific subgroups: Age (≤ 65 years vs > 65 years); American Society of Anesthesiologists physical status classification score (II vs III); Mini-Mental State Examination (≤ 26 vs > 26); history of smoking (yes vs no); frailty (robust vs prefrail or frail); hemoglobin (non-anemia vs anemia); albumin (≤ 39 vs > 39); Athens Insomnia Scale (≤ 3 vs > 3); duration of surgery (≤ 180 vs > 180). OR: Odds ratio; CI: Confidence interval; ASA: American Society of Anesthesiologists; MMSE: Mini-Mental State Examination; AIS: Athens Insomnia Scale.