Table 3. Multivariate analysis of prognostic factors (before and after PSM).

Variables	Before PSM				After PSM
	HR	95% CI	P		HR	95% CI	P
Age (years)
<50	1				1
≥50	1.119	0.989–1.268	0.075		1.142	0.969–1.347	0.113
Race/ethnicity
Non-Hispanic White	1				1
Non-Hispanic Black	1.254	1.062–1.482	0.008		1.141	0.899–1.448	0.278
Hispanic (all races)	0.943	0.777–1.144	0.550		0.730	0.540–0.987	0.041
Other	0.839	0.676–1.040	0.109		0.880	0.645–1.201	0.420
Grade
Well differentiated	1				1
Moderately differentiated	1.905	1.281–2.832	0.001		1.825	0.891–3.739	0.100
Poorly/undifferentiated	2.857	1.929–4.233	<0.001		3.060	1.501–6.238	0.002
Tumor stage
T1	1				1
T2	1.846	1.607–2.120	<0.001		1.925	1.564–2.369	<0.001
Number of positive lymph nodes (n)
1	1				1
2	1.125	0.979–1.292	0.097		0.968	0.804–1.164	0.727
3	1.234	1.059–1.438	0.007		1.105	0.901–1.355	0.338
ER status
Negative	1				1
Positive	0.805	0.676–0.958	0.015		0.796	0.611–1.039	0.093
PR status
Negative	1				1
Positive	0.555	0.466–0.661	<0.001		0.553	0.422–0.724	<0.001
Marital status
Unmarried	1				1
Married	0.862	0.761–0.977	0.020		0.845	0.718–0.995	0.044
PMRT
No	1				1
Yes	1.089	0.960–1.235	0.186		1.129	0.962–1.324	0.137

CI, confidence interval; ER, estrogen receptor; HR, hazard ratios; PMRT, postmastectomy radiotherapy, PR, progesterone receptor; PSM, propensity score matching.