Table 2.

Age-Adjusted Mean (SE) Percent Breast Density According to Strata of Sociodemographic, Hormonal, and Lifestyle Characteristics (n = 95)

Characteristic	n	Mean	(SE)	p valuea
Age, years				0.0002
40–45	24	27.0	1.9
46–50	14	21.7	2.5
51–55	23	19.9	1.9
56–60	19	18.2	2.1
61	15	12.6	2.4
Cigarette smoking				0.39
Never or past	88	20.7	1.0
Current	7	17.5	3.5
BMI (kg/m2)				0.008
21.7–26.7	23	24.7	1.8
26.8–30.5	24	22.3	1.8
30.6–34.1	24	18.5	1.8
34.2–49.5	24	16.5	1.8
Sitting (min/wk)				0.68
275–960	24	19.0	1.9
961–1,409	24	20.5	1.9
1,410–1,899	23	22.3	1.9
1,900–4,800	24	20.2	1.9
Total physical activity (MET-min/wk)				0.30
0–1,049		23	19.0	2.0
1,050–2,699	24	22.5	1.9
2,700–4,999	24	22.0	1.9
5,000–13,536	24	18.4	1.9
Insulin (μU/mL)				0.64
6.6–12.7	23	22.3	1.9
12.8–18.9	24	18.7	1.9
19.0–26.4	24	20.6	1.9
26.5–72.4	24	20.4	1.9
HOMA index				0.66
1.6–3.1	23	21.5	1.9
3.2–5.2	24	19.0	1.9
5.3–7.2	24	21.8	1.9
7.3–37.7	24	19.6	1.9

^ap value from ANCOVA