Table 1.

Characteristics of postmenopausal NHS participants at baseline in 2000 according to statin exposure (n = 77,845)

CharacteristicStatin users (n = 15,151)Nonusers (n = 62,694)
Age, mean (SD)68.1 (6.6)66.1 (7.0)
Age at menarche, mean (SD)12.5 (1.8)12.4 (1.8)
Age at menopause, mean (SD)49.4 (5.2)49.4 (5.8)
Personal history of BBD, n (%)7,711 (51)31,079 (50)
First-degree family history of breast cancer, n (%)2,560 (17)9,393 (15)
BMI, mean (SD)
 Number of missing observations27.8 (5.2)26.7 (5.4)
Reproductive history
 Nulliparous, n (%)760 (5.0)3,371 (5.4)
 Parity, mean (SD)a3.2 (1.5)3.2 (1.5)
 Age at first birth, mean (SD)a25.1 (3.3)25.0 (3.3)
 (Missing)2321,120
MHT, n (%)
 Never used hormones3,425 (24)13,626 (22)
 Former user4,367 (31)15,531 (25)
 Current user, duration <5 years1,059 (7.5)5,323 (8.5)
 Current user, duration ≥5 years5,336 (38)23,863 (38)
 (Missing)9644,351
Co-medications, n (%)
 Aspirin4,987 (33)13,019 (21)
 Ibuprofen3,979 (26)14,867 (24)
 Beta-blockers3,969 (26)7,268 (12)
 Calcium channel blockers2,452 (16)4,467 (7.1)
 ACE inhibitors2,782 (18)5,351 (8.5)
 Tamoxifen (preventive)943 (6.2)3,216 (5.1)
 Digoxin651 (4.3)1,352 (2.2)
Diabetes history, n (%)1,789 (12)3,441 (5.5)
Screening mammogram in past 2 years, n (%)14,048 (93)48,803 (78)
Alcohol consumption, median (q1–q3)1.7 (0.2–6.3)2.0 (0.3–7.7)
Number of missing observations2332,482
Physical activity, weekly metabolic equivalents
 METs < 34,045 (27)12,367 (23)
 (3 ≤ METs < 9)3,610 (24)11,830 (22)
 (9 ≤ METs < 18)2,994 (20)10,822 (20)
 (18 ≤ METs < 27)1,790 (12)6,816 (13)
 METs ≥ 272,544 (17)11,221 (21)
 (Missing)1689,638
  • aAmong parous women. Age at first birth (AFB) and parity were converted into a categorical variable with the following categories: nulliparous, 1 or 2 children and AFB ≤30, 1 or 2 children and AFB >30, 3 or 4 children and AFB ≤30, 3 or 4 children and AFB >30, 5 or more children and AFB ≤30, and 5 or more children and AFB >30.