Table 3.

Results of Univariate and Multivariable Logistic Regression Models for the Log Odds of Undergoing Mastectomy As Opposed to BCS

Variable	Univariate Results			Multivariable Results
	Odds Ratio	95% CI	P	Odds Ratio	95% CI	P
Preoperative breast MRI, yes v no	1.9	1.5 to 2.4	< .0001	1.7	1.3 to 2.2	< .0001
Calendar year
1997 v 2003	1.8	1.4 to 2.3	< .0001	2.0	1.5 to 2.6	< .0001
1998 v 2003	1.7	1.3 to 2.2	< .0001	2.1	1.6 to 2.7	< .0001
1999 v 2003	1.5	1.2 to 1.9	.0007	1.7	1.3 to 2.2	< .0001
2000 v 2003	1.3	1.0 to 1.7	.02	1.4	1.1 to 1.8	.01
2001 v 2003	1.3	1.0 to 1.6	.06	1.4	1.1 to 1.8	.01
2002 v 2003	1.2	1.0 to 1.6	.08	1.4	1.1 to 1.8	.02
2004 v 2003	1.3	1.0 to 1.7	.02	1.4	1.1 to 1.8	.01
2005 v 2003	1.8	1.4 to 2.3	< .0001	1.8	1.4 to 2.4	< .0001
2006 v 2003	1.7	1.3 to 2.2	< .0001	1.7	1.3 to 2.2	.0001
Age, years
≥ 50 v < 50	0.74	0.65 to 0.84	< .0001	0.80	0.70 to 0.92	.001
TNM stage
TNM 1 v 0	0.9	0.8 to 1.1	.34	0.9	0.7 to 1.0	.09
TNM 2 v 0	2.1	1.8 to 2.4	< .0001	2.0	1.7 to 2.4	< .0001
Primary histology
Lobular v ductal	1.6	1.4 to 2.0	< .0001	1.6	1.3 to 1.9	< .0001
Other invasive v ductal	1.1	0.9 to 1.4	.40	1.2	1.0 to 1.6	.09
Breast density
4 v 1, 2, 3	1.6	1.2 to 2.0	.0001	1.5	1.1 to 1.9	.002
Unknown v 1, 2, 3	1.1	1.0 to 1.3	.04	1.0	0.9 to 1.1	.86
Concurrent or prior contralateral breast cancer
Yes v no	3.2	2.6 to 3.8	< .0001	3.8	3.1 to 4.5	< .0001
Laterality
Left v right	1.2	1.0 to 1.3	.007	1.2	1.0 to 1.3	.005
First-degree family history of breast cancer
Yes v no	1.1	1.0 to 1.3	.05	1.2	1.0 to 1.3	.04

Abbreviation: MRI, magnetic resonance imaging.