Figure 4.
Cumulative number of events (annualized percentages) and hazard ratios (HRs [95% confidence intervals] for endometrial cancer incidence) in the Women’s Health Initiative randomized trial of continuous combined estrogen plus progestin by baseline characteristics and random assignment. Hazard ratios, 95% confidence intervals, and P values are from Cox proportional hazards models stratified according to age and random assignment in the dietary modification trial. Dotted line represents overall hazard ratio for endometrial cancer incidence attributed to estrogen plus progestin. P value is from a one degree-of-freedom score x2 test of the interaction between the given subgroup and random assignment. Estrogen indicates conjugated equine estrogens, and progestin indicates medroxyprogesterone acetate. Number of events may not add up because of missing baseline data. All statistical tests were two-sided. BMI = body mass index; CI = confidence interval; HR = hazard ratio.