LAUSR

The health benefits and risks of menopausal hormone therapy among women aged 50-59 years are examined in the Women's Health Initiative randomized, placebo-controlled trials using long-term follow-up data and a parsimonious statistical model that leverages data from older participants to increase precision. These trials enrolled 27,347 healthy post-menopausal women aged 50-79 at 40 U.S. clinical centers during 1993-1998, including 10,739 post-hysterectomy participants in a trial of conjugated equine estrogens, and 16,608 participants with uterus in the trial of these estrogens plus medroxyprogesterone acetate. Over an 18-year (median) follow-up period (1993-2016) risk for a global index, defined as the earliest of coronary heart disease, invasive breast cancer, stroke, pulmonary embolism, colorectal cancer, endometrial cancer, hip fracture, and all-cause mortality, is reduced with conjugated equine estrogens with hazard ratio (95% confidence interval) of 0.82 (0.71, 0.95), and with nominally significant reductions for coronary heart disease, breast cancer, hip fracture and all-cause mortality. Corresponding global index hazard ratio estimates of 1.06 (0.95, 1.19) were non-significant for combined estrogens plus progestin, but increased breast cancer risk and reduced endometrial cancer risk were observed. These results, among women 50-59, substantially agree with the worldwide observational literature, with the exception of breast cancer for estrogens alone.