Effects of balanced opioid-free anesthesia on post-operative nausea and vomiting in patients undergoing video-assisted thoracic surgery: a randomized trial

Table 1 Baseline characteristics

Variables	OFA group n = 82	OBA group n = 83	ASD
Demographics
Age, year	56[50,60]	56[50,60]	0.043
Female sex	47(57.3%)	55(66.3%)	0.146
Body mass index, kg/m²	24.5 ± 3.5	23.9 ± 3.6	0.169
Preoperative comorbidities
Smoker	17(20.7%)	12(14.5%)	0.163
Alcoholism^a	10(12.2%)	7(8.4%)	0.125
Hypertension	29(35.4%)	21(25.3%)	0.220
Diabetes	14(17.1%)	9(10.8%)	0.182
Coronary artery disease	4(4.9%)	4(4.8%)	0.005
Chronic obstructive pulmonary disease	3(3.7%)	2(2.4%)	0.076
Hyperlipidemia	18(22.0%)	21(25.3%)	0.078
Pulmonary disease
Side of lesion (left/right)	36/46	35/48	0.034
Maximum diameter of lesion, mm	14[10,24]	13[10,18]	0.239
Lung cancer	68(82.9%)	67(80.7%)	0.057
FEV1/FVC%	77[74,80]	77[74,80]	0.017
Baseline assessment
age-adjusted Charlson Comorbidity Index	1[1,2]	1[1,2]	0.187
ASA physical status			0.236
I	29(35.4%)	39(47.0%)
II	49(59.7%)	40(48.2%)
III	4(4.9%)	4(4.8%)
6-MWT, meter	461[415,514]	450[408,500]	0.044
KPS status, point	100[90,100]	100[100,100]	0.219
Apfel score			0.242
1	16(19.5%)	9(10.8%)
2	14(17.1%)	11(13.3%)
3	34(41.4%)	40(48.2%)
4	18(22.0%)	23(27.7%)

Data are mean ± standard deviation, median [inter-quartile range], or n (%). An absolute standardized difference > 0.305 is considered imbalanced between the two groups. ^aTwo drinks or more daily, or weekly consumption of the equivalent of 150 ml of alcohol. OFA Opioid-free anesthesia, OBA Opioid-based anesthesia, SMD Absolute standardized difference, ASA American Society of Anesthesiologists, 6-MWT 6-minute walk test, KPS Karnofsky Performance Status Scale. Apfel score including four variables (female sex, non-smoking status, history of PONV or motion sickness, and use of postoperative opioids) that are assigned one point each, and the total score was used to evaluate the risk of developing PONV

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