Colorectal adenocarcinoma patients with M1a diseases gain more clinical benefits from palliative primary tumor resection than those with M1b diseases: A propensity score matching analysis

Table 2 Univariate and multivariate cox regression analyses for overall survival of metastatic colorectal adenocarcinoma patients

	M1a				M1b
	Univariate analysis		Multivariate analysis		Univariate analysis		Multivariate analysis
	HR (95%CI)	P value	HR (95%CI)	P value	HR (95%CI)	P value	HR (95%CI)	P value
Gender
Female	Reference		Reference		Reference		Reference
Male	1.100 (1.054-1.147)	< 0.001	1.025 (0.975-1.077)	0.339	1.043 (1.002-1.086)	0.042	1.020 (0.972-1.070)	0.428
Year of diagnosis
2010-2012	Reference		Reference		Reference		Reference
2013-2015	0.972 (0.929-1.016)	0.208	0.981 (0.929-1.036)	0.486	0.965 (0.925-1.006)	0.096	0.972 (0.924-1.023)	0.277
Age (years)
< 65	Reference		Reference		Reference		Reference
≥ 65	1.675 (1.606-1.746)	< 0.001	1.413 (1.344-1.485)	< 0.001	1.527 (1.466-1.589)	< 0.001	1.319 (1.256-1.385)	< 0.001
Race
White	Reference		Reference		Reference		Reference
Black	1.138 (1.075-1.206)	< 0.001	1.114 (1.042-1.192)	0.002	1.127 (1.068-1.191)	< 0.001	1.137 (1.064-1.215)	< 0.001
Others	0.910 (0.844-0.981)	0.013	0.864 (0.792-0.942)	0.001	0.953 (0.891-1.020)	0.164	0.952 (0.878-1.031)	0.227
Marital status
Married	Reference		Reference		Reference		Reference
Others	1.326 (1.272-1.383)	< 0.001	1.142 (1.086-1.201)	< 0.001	1.212 (1.165-1.262)	< 0.001	1.078 (1.026-1.132)	0.003
Primary site
Colon	Reference		Reference		Reference		Reference
Rectum	0.799 (0.758-0.841)	< 0.001	0.759 (0.711-0.811)	< 0.001	0.839 (0.797-0.882)	< 0.001	0.779 (0.731-0.830)	< 0.001
Grade
I + II	Reference		Reference		Reference		Reference
III + IV	1.530 (1.450-1.614)	< 0.001	1.580 (1.484-1.682)	< 0.001	1.447 (1.375-1.523)	< 0.001	1.506 (1.417-1.601)	< 0.001
Others	1.702 (1.614-1.795)	< 0.001	1.149 (1.074-1.228)	< 0.001	1.544 (1.473-1.619)	< 0.001	1.178 (1.109-1.251)	< 0.001
Surgery
Yes	Reference		Reference		Reference		Reference
No	1.953 (1.859-2.051)	< 0.001	2.133 (2.011-2.262)	< 0.001	1.632 (1.552-1.716)	< 0.001	1.955 (1.843-2.074)	< 0.001
Chemotherapy
Yes	Reference		Reference		Reference		Reference
No/unknown	2.520 (2.395-2.651)	< 0.001	2.282 (2.164-2.405)	< 0.001	2.558 (2.430-2.692)	< 0.001	2.565 (2.432-2.705)	< 0.001
Radiotherapy
Yes	Reference		Reference		Reference		Reference
No	2.337 (2.069-2.639)	< 0.001	1.236 (1.085-1.408)	0.001	1.695 (1.465-1.961)	< 0.001	0.946 (0.813-1.101)	0.472

HR: Hazard ratio; CI: Confidence interval.