Skip to main content
. Author manuscript; available in PMC: 2012 Mar 29.
Published in final edited form as: Epidemiology. 2010 Jul;21(4):528–539. doi: 10.1097/EDE.0b013e3181df1b69

Table 2.

Intention-to-treat average hazard ratios (HR) and risk differences (RD) (cases per 100 women) and their 95% confidence intervals (CIs) of invasive breast cancer, Women’s Health Initiative estrogen-plus-progestin (E+P) randomized triala

Follow-up period

0–2 years 0–6 years 0–8 years

Overall
  No. of cases; E+P/placebo 38/51 181/140 198/149
  HR (95% CI) 0.71 (0.46 to 1.08) 1.23 (0.98 to 1.53) 1.25 (1.01 to 1.54)
  RD (95% CI) −0.16 (−0.37 to 0.05) 0.53 (0.03 to 1.03) 0.83 (−0.03 to 1.69)
Prior hormone use
No
  No. of cases; E+P/placebo 22/36 127/112 140/120
  HR (95% CI) 0.59 (0.34 to 1.00) 1.08 (0.84 to 1.39) 1.10 (0.86 to 1.40)
  RD (95% CI) −0.25 (−0.47 to −0.02) 0.27 (−0.33 to 0.87) 0.46 (−0.63 to 1.55)
Yes
  No. of cases; E+P/placebo 16/15 54/28 58/29
  HR (95% CI) 1.02 (0.51 to 2.07) 1.82 (1.15 to 2.87) 1.87 (1.20 to 2.92)
  RD (95% CI) 0.11 (−0.36 to 0.57) 1.31 (0.47 to 2.15) 1.84 (0.62 to 3.06)
Years since menopauseb
< 10
  No. of cases; E+P/placebo 15/18 52/40 55/43
  HR (95% CI) 0.80 (0.41 to 1.60) 1.26 (0.83 to 1.90) 1.23 (0.83 to 1.84)
  RD (95% CI) −0.11 (−0.47 to 0.24) 0.42 (−0.37 to 1.20) 0.48 (−0.61 to 1.57)
≥ 10
  No. of cases; E+P/placebo 20/31 109/91 118/95
  HR (95% CI) 0.63 (0.36 to 1.10) 1.17 (0.89 to 1.55) 1.21 (0.93 to 1.59)
  RD (95% CI) −0.22 (−0.51 to 0.07) 0.57 (−0.09 to 1.24) 1.09 (−0.38 to 2.57)
Age group
< 60
  No. of cases; E+P/placebo 10/15 47/35 52/39
  HR (95% CI) 0.62 (0.28 to 1.38) 1.25 (0.81 to 1.94) 1.23 (0.81 to 1.86)
  RD (95% CI) −0.16 (−0.47 to 0.15) 0.41 (−0.28 to 1.10) −0.19 (−1.51 to 1.14)
≥ 60
  No. of cases; E+P/placebo 28/36 134/105 146/110
  HR (95% CI) 0.74 (0.45 to 1.22) 1.22 (0.94 to 1.57) 1.25 (0.98 to 1.61)
  RD (95% CI) −0.15 (−0.42 to 0.12) 0.64 (0.01 to 1.27) 1.46 (0.39 to 2.53)
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

HHS Vulnerability Disclosure