TABLE 4.

Univariate and multivariate regression analyses of length of stay

Characteristic	Univariate analysis			Hierarchical multivariate analysisa
	Coefficient	95% CI	p-value	Coefficient	95% CI	p-value
Age (continuous)	0.009	0.001, 0.016	0.030	0.008	0.008, 0.008	<0.001
Sex, male	Reference
Sex, female	−0.146	−0.314, 0.022	0.089
BMI (continuous)	−0.016	−0.040, 0.007	0.174
ASA score, I and II	Reference			Reference
ASA score, III and IV	−0.540	−0.741, −0.338	<0.001	−0.015	−0.359, 0.330	0.934
Previous abdominal surgery, no	Reference			Reference
Previous abdominal surgery, yes	−0.600	−0.739, −0.462	<0.001	−0.189	−0.491, 0.114	0.221
Chemotherapy preoperatively, no	Reference			Reference
Chemotherapy preoperatively, yes	−0.403	−0.560, −0.247	<0.001	−0.013	−0.334, 0.308	0.937
Region, East	Reference
Region, West	−0.750	−0.894, −0.607	<0.001
Histopathology
CRLM	Reference			Reference
HCC	0.683	0.536, 0.830	<0.001	0.174	0.169, 0.180	<0.001
Benign	−0.456	−0.915, 0.004	0.052	0	b
CCC	1.100	0.679, 1.521	<0.001	0.428	0.288, 0.568	<0.001
Other metastasis	−0.142	−0.420, 0.135	0.315	−0.063	−0.064, −0.062	<0.001
Combined HCC/CCC	0.415	−0.020, 0.850	0.061	0	b
Lesion origin
Primary	Reference			Reference
Metastatic	−0.720	−0.856, −0.584	<0.001	−0.206	−0.246, −0.167	<0.001
Benign	−1.145	−1.598, −0.693	<0.001	−0.241	−0.343, −0.139	<0.001
Approach, open	Reference			Reference
Approach, robotic	−0.930	−1.101, −0.759	<0.001	−0.668	−0.859, −0.477	<0.001

^aData clustered by region

^bOmitted because of collinearity

ASA American Society of Anesthesiologists, BMI body mass index, CRLM colorectal liver metastases, CCC cholangiocarcinoma, CI confidence interval, HCC hepatocellular carcinoma