Prognostic factors of survival and a new scoring system for liver resection of colorectal liver metastasis

Table 2 Univariate analysis of factors associated with overall survival

Variable	HR	95%CI	P value
Age	1.015	0.984-1.047	0.350
Sex
Male	Ref
Female	1.259	0.733-1.162	0.405
Location of primary tumor
Rectum	Ref
Right	1.542	0.780-3.048	0.213
Left	1.370	0.737-2.545	0.319
Regional LN metastasis
No	Ref
Yes	1.444	0.836-2.492	0.187
Time of diagnosis of liver metastasis, %
Synchronous	Ref
Metachronous
Disease-free interval < 12 mo	0.814	0.317-2.094	0.670
Disease-free interval ≥ 12 mo	0.750	0.416-1.352	0.338
Synchronous extrahepatic metastasis
No	Ref
Yes	1.884	0.253-14.0	0.536
Preoperative CEA level
< 200 ng/mL	Ref
≥ 200 ng/mL	1.104	0.392-3.111	0.851
Systemic chemotherapy before liver resection
No	Ref
Yes	1.104	0.439-2.776	0.833
Number of liver metastases
< 5 lesions	Ref
≥ 5 lesions	2.506	1.124-5.585	0.025a
Size of the largest liver lesion
< 4 cm	Ref
≥ 4 cm	1.645	0.934-2.896	0.085
Surgical margin
Clear	Ref
Involved	0.965	0.509-1.829	0.912
Concurrent ablation
No	Ref
Yes	1.449	0.573-3.663	0.434
Operative approach
Laparoscopic	Ref
Open	1.069	0.624-1.832	0.808
Intraoperative blood loss, %
< 500 mL	Ref
≥ 500 mL	1.845	0.985-3.457	0.056
Requirement of blood transfusion, %
No	Ref
Yes	1.326	0.712-2.472	0.374

^aP < 0.05. CEA: Carcinoembryonic antigen; CI: Confidence interval; HR: Hazard ratio; LN: Lymph node; Ref: Reference.