Table 1.
Baseline characteristics by body mass index group (kg/m2) in the IBIS-I and IBIS-II prevention trials
| IBIS-I (tamoxifen vs. placebo) (N = 6903) | IBIS-II (anastrozole vs. placebo) (N = 3750) | |||||
|---|---|---|---|---|---|---|
| BMI < 25 (N = 2878, 41.7%) |
BMI: 25–29.9 (N = 2391, 34.6%) |
BMI > 30 (N = 1634, 23.7%) |
BMI < 25 (N = 1140, 30.4%) |
BMI: 25–29.9 (N = 1420, 37.9%) |
BMI > 30 (N = 1190, 31.7%) |
|
| Randomised to preventive therapy (%) | 50.3 | 49.0 | 50.7 | 50.2 | 48.9 | 50.1 |
| HRT usea (%) | 26.4 | 26.7 | 24.0 | 46.3 | 48.4 | 46.7 |
| Current/history of smoking (%) | 20.7 | 18.2 | 14.5 | 14.9 | 9.9 | 8.9 |
| Postmenopausal (%) | 50.5 | 57.9 | 54.9 | 100 | 100 | 100 |
| 10-year Tyrer-Cuzick % risk, median (IQR)b | 5.5 (4.4–7.0) | 5.8 (4.7–7.5) | 6.0 (4.7–7.7) | 7.0 (5.3–9.2) | 8.0 (6.1–10.2) | 8.0 (6.0–10.5) |
| Age (years), median (IQR) | 49 (45–53) | 50 (46–56) | 49 (45–53) | 59 (54–63) | 60 (56–64) | 60 (55–63) |
BMI kg/m2, IQR interquartile range, HRT hormone replacement therapy
aIn IBIS-I, HRT was either current or previous use, whereas in IBIS-II, it was previous HRT use only
bMissing IBIS-I: N = 221; IBIS-II N = 73