Table 1.
Descriptive characteristics of study cohort of 24,840 women.
| N | (%) | |
|---|---|---|
| FFDM machine type | ||
| Hologic | 20,877 | (84.0) |
| GE | 3,963 | (16.0) |
| Age, Mean (IQR) | 61.5 | (56.0–68.0) |
| BMI (kg/m2), Mean (IQR) | 27.6 | (23.2–30.7) |
| Late adolescent BMI (kg/m2), Mean (IQR) | 21.1 | (19.3–22.3) |
| Menopause (based on survey) | ||
| Pre-menopause | 4,835 | (19.5) |
| Post-menopause | 20,005 | (80.5) |
| Menopausal Hormone Therapy in last 5 years | ||
| No (includes pre-menopausal women) | 18,680 | (75.2) |
| Yes | 6,160 | (24.8) |
| Parity | ||
| Nulliparous | 2,318 | (9.3) |
| One child | 3,662 | (14.7) |
| Two children | 9,217 | (37.1) |
| Three children | 4,168 | (16.8) |
| Four or more children | 2,045 | (8.2) |
| Missing | 3,430 | (13.8) |
| Age at first birth | ||
| Have not given birth | 2,318 | (9.3) |
| <20 years | 2,584 | (10.4) |
| 20–24 years | 6,734 | (27.1) |
| 25–29 years | 5,502 | (22.2) |
| 30–34 years | 2,748 | (11.1) |
| 35–40 years | 1,133 | (4.6) |
| >40 years | 252 | (1.0) |
| Missing | 3,569 | (14.4) |
| Age at menarche | ||
| <10 years | 491 | (2.0) |
| 10–11 years | 4,617 | (18.6) |
| 12–13 years | 13,177 | (53.1) |
| 14–15 years | 4,147 | (16.7) |
| >16 years | 920 | (3.7) |
| Never had a menstrual period | 10 | (<0.1) |
| Missing | 1,478 | (5.9) |
| Family history of breast cancer | ||
| No | 22,505 | (90.6) |
| Yes | 2,335 | (9.4) |
| Percent Density (%), Mean (IQR) | 21.0 | (8.1–31.1) |
| Dense Area (cm2), Mean (IQR) | 28.0 | (14.4–37.0) |