Table 2.

Multivariable binary logistic regression model of variables associated with first-line mastectomy

		p value	Odds ratio	95% CI
MRI referral	noMRI	Reference	–	–
	Screening MRI	< 0.001	2.5	1.5–4.0
	Diagnostic MRI	0.300	1.2	0.9–1.5
	Preoperative MRI	< 0.001	2.2	1.9–2.5
Breast density	ACR BI-RADS class a	Reference	–	–
	ACR BI-RADS class b	0.498	1.1	0.9–1.4
	ACR BI-RADS class c	0.168	1.2	0.9–1.5
	ACR BI-RADS class d	0.001	1.7	1.2–2.3
Breast cancer risk	Familial breast cancer risk	0.012	2.0	1.2–3.3
Hormonal status	Postmenopausal	Reference	–	–
	Premenopausal	< 0.001	1.6	1.4–1.9
	Perimenopausal	0.247	1.2	0.9–1.5
Lesion focus at DM	No observable lesion	Reference	–	–
	Single focus	< 0.001	0.7	0.5–0.8
	Multifocal	0.211	1.2	0.9–1.7
	Multicentric	0.001	2.4	1.4–4.2
Largest lesion diameter at DM	≥ 20 mm	< 0.001	2.0	1.7–2.4
Lesion focus at US	No observable lesion	Reference	–	–
	Single focus	0.336	0.9	0.7–1.1
	Multifocal	< 0.001	2.4	1.8–3.3
	Multicentric	< 0.001	5.8	3.2–10.8
Largest lesion diameter at US	≥ 20 mm	< 0.001	2.1	1.7–2.5
Core-needle or vacuum-assisted biopsy	Pure DCIS	0.196	1.1	0.9–1.4
	Lobular component	< 0.001	1.7	1.4–2.1

CI, confidence interval; ACR BI-RADS, American College of Radiology Breast Imaging Data and Reporting System; DM, digital mammography; US, ultrasonography; MRI, magnetic resonance imaging; DCIS, ductal carcinoma in situ