Table 1.

Subject characteristics by statin use

Characteristics	Statin use*
	Nonuser (n = 16,611)	Discontinuer (n = 84)	Initiator (n = 452)	Continuer (n = 1,000)
Age at 1st screen, mean (SD), y	62.5 (8.5)	65.8 (7.6)	65.1 (8.2)	66.6 (7.7)
BMI at 1st screen, mean (SD), kg/m2	27.7 (6.5)	30.2 (5.2)	29.5 (6.5)	29.4 (6.1)
Race (%)
White	91.8	86.9	93.1	91.1
Black	2.5	3.6	2.2	3.0
Asian/Pacific Islander	4.9	7.1	4.0	5.4
Other/unknown	0.8	2.4	0.7	0.5
Unit change (kg/m2) in BMI (%)
No change	57.3	51.2	54.9	53.2
Decrease of ≥1 units	19.2	23.8	24.3	22.9
Increase of ≥1 units	23.5	25.0	20.8	23.9
Family history of breast cancer	39.4	46.4	37.4	36.8
Parous	85.3	84.5	86.3	88.1
Age at menopause, y (%)
<30	6.0	4.8	6.0	4.7
30–39	11.3	15.5	12.4	13.7
40–49	37.7	45.2	35.2	40.1
50–59	44.2	34.5	44.4	40.6
≥60	0.8	0.0	2.0	0.9
Hormone use (%)
Never user	41.5	40.4	50.2	42.9
Discontinuer	7.9	16.7	7.5	8.3
Initiator	4.0	1.2	5.1	2.2
Continuer	46.6	41.7	37.2	46.6
BI-RADS breast density category at 1st screen (%)
Almost entirely fat	7.7	10.7	13.1	12.5
Scattered fibroglandular tissue	42.5	53.5	49.3	49.0
Heterogeneously dense	42.6	33.3	35.2	35.0
Extremely dense	7.3	2.4	2.4	3.5
Change in BI-RADS breast density category (%)
No change	66.4	60.7	66.8	64.3
Decrease of ≥1 categories	17.4	17.9	16.4	17.2
Increase of ≥1 categories	16.2	21.4	16.8	18.5

^*We defined nonusers as women who were not using statins at either screen, discontinuers as users of statins at the 1st screen but nonusers at the 2nd screen, initiators as nonusers of statins at the 1st screen but users of statins at the 2nd screen, and continuers as users of statins at both screens.