Table 1

Comparison of cases and controls by selected demographic and risk factors among postmenopausal Iowa women

Participants who provided a blood sampleAll study participants
Cases (n = 156)Controls (n = 332)OR (95% CI)Cases (n = 273)Controls (n = 657)OR (95% CI)
Demographic and major risk factors
Age ≥65 years at baseline33641.1 (0.7–1.8)701441.2 (0.9–1.7)
Education ≥ high school811531.3 (0.9–1.9)1282771.2 (0.9–1.6)
First-degree relatives with breast cancer26381.5 (0.9–2.7)47681.8 (1.2–2.7)
WHR ≥ 0.85711091.7 (1.2–2.5)1272301.6 (1.2–2.2)
BMI ≥ 26851691.2 (0.8–1.7)1593231.4 (1.1–1.9)
Menarche at ≤ 13 years1162401.1 (0.7–1.7)2034701.2 (0.8–1.6)
Menopause at ≥ 55 years18311.3 (0.7–2.3)30661.1 (0.7–1.7)
Live birth < 41061801.8 (1.2–2.7)1803761.4 (1.1–1.9)
First live birth ≥ 22 years911771.2 (0.8–1.8)1553541.1 (0.8–1.5)
Alcohol drinking661520.9 (0.6–1.3)1182940.9 (0.7–1.2)
Meat doneness level
Rare/medium341221.0 (reference)602241.0 (reference)
Mostly well done41731.8 (1.1–1.9)711551.5 (1.03–2.2)
Consistently well/very well done651032.0 (1.3–3.1)1132121.7 (1.2–2.4)
P for trend, 0.001P for trend, <0.001