Table 1 Participant baseline characteristics by case and control status
Characteristics | Total N = 1222 | Cases N = 323 | Controls N = 899 |
|---|---|---|---|
N (%) or mean ± SD | N (%) or mean ± SD | N (%) or mean ± SD | |
Age at baseline, y | 47.9 ± 5.0 | 48.2 ± 4.9 | 47.8 ± 5.1 |
Age at first mammogram, y | 50.4 ± 5.3 | 49.6 ± 5.1 | 50.7 ± 5.4 |
Family history of breast cancer | |||
0 first-degree relatives (half sisters) | 41 (3.4) | 10 (3.1) | 31 (3.4) |
1 first-degree relatives | 850 (69.6) | 191 (59.1) | 659 (73.3) |
≥ 2 first-degree relatives | 331 (27.1) | 122 (37.8) | 209 (23.2) |
Family history of breast cancer, first- or second-degree | |||
1 first- or second-degree relatives | 541 (44.3) | 114 (35.3) | 427 (47.5) |
2 first- or second- degree relatives | 428 (35.0) | 119 (36.8) | 309 (34.4) |
≥ 3 first- or second-degree relatives | 253 (20.7) | 90 (27.9) | 163 (18.1) |
Age at diagnosis for first degree relatives | 44.5 ± 7.8 | 44.4 ± 7.8 | 44.5 ± 7.8 |
< 40 | 290 (24.6) | 81 (25.9) | 209 (24.1) |
40–49 | 600 (50.8) | 151 (48.2) | 449 (51.7) |
≥ 50 | 289 (24.5) | 81 (25.9) | 208 (24.0) |
Missing | 2 (0.2) | 2 (0.2) | |
5-year BOADICEA risk score | 2.1 ± 0.8 | 2.2 ± 0.9 | 2.0 ± 0.8 |
Low risk (< 1.67%) | 397 (32.5) | 84 (26.0) | 313 (34.8) |
High risk (≥ 1.67%) | 816 (66.8) | 237 (73.4) | 579 (64.4) |
Missing | 9 (0.7) | 2 (0.6) | 7 (0.8) |
Menopausal status at baseline | |||
Pre | 830 (67.9) | 219 (67.8) | 611 (68.0) |
Post | 392 (32.1) | 104 (32.2) | 288 (32.0) |
Menopausal status at the end of Follow-up | |||
Pre | 275 (22.5) | 120 (37.2) | 155 (17.2) |
Post | 944 (77.2) | 201 (62.2) | 743 (82.6) |
Missing | 3 (0.2) | 2 (0.6) | 1 (0.1) |
Hormone replacement Therapy use | |||
Never users | 952 (77.9) | 253 (78.3) | 699 (77.8) |
Former users | 168 (13.7) | 40 (12.4) | 128 (14.2) |
Current users | 99 (8.1) | 30 (9.2) | 69 (7.7) |
Missing | 3 (0.2) | 3 (0.3) | |
Number of live birth | 2.2 ± 0.9 | 2.2 ± 0.9 | 2.2 ± 0.9 |
0 (no live birth) | 280 (22.9) | 76 (23.5) | 204 (22.7) |
1 | 172 (14.1) | 51 (15.8) | 121 (13.5) |
2 | 476 (39.0) | 120 (37.2) | 356 (39.6) |
≥ 3 | 294 (24.1) | 76 (23.5) | 218 (24.2) |
Age at first birth (in parous women), y | 26.2 ± 5.4 | 26.6 ± 5.2 | 26.1 ± 5.4 |
< 25 | 385 (40.9) | 94 (38.1) | 291 (41.9) |
25—29 | 313 (33.2) | 86 (34.8) | 227 (32.7) |
≥ 30 | 244 (25.9) | 67 (27.1) | 177 (25.5) |
Breastfeeding duration (in parous women), wk | 59.1 ± 73.6 | 57.4 ± 68.4 | 59.8 ± 75.5 |
Live Birth, No Breastfeeding | 156 (16.6) | 34 (13.8) | 122 (17.6) |
< 12 | 122 (13.0) | 40 (16.2) | 82 (11.8) |
≥ 12–< 26 | 133 (14.1) | 31 (12.6) | 102 (14.7) |
≥ 26–< 52 | 155 (16.5) | 46 (18.6) | 109 (15.7) |
≥ 52—< 78 | 131 (13.9) | 30 (12.1) | 101 (14.5) |
≥ 78 | 244 (25.9) | 66 (26.7) | 178 (25.6) |
Age at menarche, y | 12.7 ± 1.5 | 12.7 ± 1.5 | 12.7 ± 1.4 |
Body mass index, Kg/m2 | 27.3 ± 6.2 | 26.7 ± 5.6 | 27.5 ± 6.4 |
< 25 | 549 (44.9) | 156 (48.3) | 393 (43.7) |
25–29.9 | 354 (29.0) | 94 (29.1) | 260 (28.9) |
≥ 30 | 318 (26.0) | 73 (22.6) | 245 (27.3) |
Alcohol consumption | |||
Never/former drinker | 157 (12.8) | 48 (14.9) | 109 (12.1) |
Current drinker < 1 drink day | 877 (71.8) | 229 (70.9) | 648 (72.1) |
Current drinker 1–1.9 drinks/day | 124 (10.1) | 27 (8.4) | 97 (10.8) |
Current drinker 2 + drinks/day | 63 (5.2) | 19 (5.9) | 44 (4.9) |
Education | |||
≥ College graduate | 711 (58.2) | 193 (59.8) | 518 (57.6) |
Tech/some college | 385 (31.5) | 104 (32.2) | 281 (31.3) |
≤ High school | 126 (10.3) | 26 (8.0) | 100 (11.1) |
Race/ethnicity | |||
Asian, Hawaiian/Pacific Islander, Native American | 30 (2.5) | 8 (2.5) | 22 (2.4) |
Hispanic | 28 (2.3) | 8 (2.5) | 20 (2.2) |
Non-Hispanic Black | 72 (5.9) | 18 (5.5) | 54 (6.0) |
Non-Hispanic White | 1096 (89.4) | 291 (89.5) | 805 (89.3) |