Table 4.
Adherence-adjusted average hazard ratios (HR) and risk differences (RD) (cases per 100 women) and 95% confidence intervals (CIs) of invasive breast cancer, Women’s Health Initiative estrogen-plus-progestin randomized triala
| Follow-up period | |||
|---|---|---|---|
| 0–2 years | 0–6 years | 0–8 years | |
| Overall | |||
| HR (95% CI) | 0.98 (0.72 to 1.33) | 1.55 (1.21 to 1.97) | 1.68 (1.24 to 2.28) |
| RD (95% CI) | −0.01 (−0.15 to 0.13) | 0.89 (0.38 to 1.41) | 1.44 (0.52 to 2.37) |
| Prior hormone use | |||
| No | |||
| HR (95% CI) | 0.92 (0.63 to 1.34) | 1.34 (1.01 to 1.78) | 1.51 (1.06 to 2.14) |
| RD (95% CI) | −0.06 (−0.22 to 0.11) | 0.73 (0.06 to 1.39) | 1.31 (0.14 to 2.48) |
| Yes | |||
| HR (95% CI) | 1.15 (0.69 to 1.91) | 1.92 (1.26 to 2.93) | 2.04 (1.27 to 3.28) |
| RD (95% CI) | 0.12 (−0.18 to 0.43) | 1.33 (0.52 to 2.14) | 1.69 (0.60 to 2.77) |
| Years since menopauseb | |||
| < 10 | |||
| HR (95% CI) | 1.30 (0.77 to 2.19) | 1.43 (0.90 to 2.27) | 1.34 (0.74 to 2.42) |
| RD (95% CI) | 0.12 (−0.13 to 0.36) | 0.66 (−0.16 to 1.47) | 0.64 (−0.75 to 2.03) |
| ≥ 10 | |||
| HR (95% CI) | 0.88 (0.60 to 1.29) | 1.52 (1.10 to 2.09) | 1.84 (1.14 to 2.99) |
| RD (95% CI) | −0.09 (−0.28 to 0.10) | 1.00 (0.23 to 1.77) | 2.13 (0.14 to 4.12) |
| Age group | |||
| < 60 | |||
| HR (95% CI) | 0.96 (0.54 to 1.71) | 1.58 (0.96 to 2.61) | 1.44 (0.84 to 2.48) |
| RD (95% CI) | 0.00 (−0.22 to 0.21) | 0.53 (−0.24 to 1.29) | 0.41 (−0.62 to 1.44) |
| ≥ 60 | |||
| HR (95% CI) | 0.99 (0.71 to 1.38) | 1.49 (1.13 to 1.97) | 1.81 (1.29 to 2.52) |
| RD (95% CI) | −0.02 (−0.20 to 0.16) | 1.11 (0.44 to 1.78) | 2.18 (0.90 to 3.45) |
a
Average hazard ratios in a given period (e.g., 0–2 years) were estimated over the entire period, while risk differences were estimated at the end of the period
b
1,420 women (827 in estrogen-plus-progestin group and 593 in placebo group) had missing years since menopause