Table 2:

Univariable analysis with proportion of blood pixels and drainage volume; multivariable linear regression model with proportion of blood pixels and log (drainage volume) (model R² = 0.228)

Characteristics	Univariable analysis			Multivariable linear regression analysis
	Regression Coefficient(β)	95% CI	P-value	Regression Coefficient(β)	95% CI	P-value
Age at surgery	10.786	5.803-15.769	< 0.001	0.005	0.001-0.008	0.005
Male	−228.153	−329.657-126.650	< 0.001
Immediate postoperative air leakage	250.608	150.735-350.482	< 0.001	0.130	0.061 ∼ 0.199	< 0.001
Surgery duration	4.099	2.977-5.220	< 0.001	0.001	0.001 ∼ 0.002	0.001
SumPBP	0.162	0.108-0.215	< 0.001
SumPBP-Flushing	1.196	0.843-1.548	< 0.001	< 0.001	< 0.001 ∼ 0.001	0.022
Clinical N stage	106.706	5.160-208.252	0.040
Bleeding volume	1.563	0.917-2.208	< 0.001	< 0.001	< 0.001 ∼ 0.001	0.033

PBP, proportion of blood pixels; SumPBP: sum of PBP; SumPBP-Flushing: sum of PBP from flushing to the end of the operation.