HEART AND ESTROGEN PROGESTIN REPLACEMENT STUDY (HERS) - DESIGN, METHODS, AND BASE-LINE CHARACTERISTICS/

The Heart and Estrogen/progestin Replacement Study (HERS) is a randomi zed, double-blind, placebo-controlled trial designed to test the effic acy and safety of estrogen plus progestin therapy for prevention of re current coronary heart disease (CHD) events in women. The participants are postmenopausal women with a uterus and with CHD as evidenced by p rior myocardial infarction, coronary artery bypass graft surgery, perc utaneous transluminal coronary angioplasty, or other mechanical revasc ularization or at least 50% occlusion of a major coronary artery. Betw een February 1993 and September 1994, 20 HERS centers recruited and ra ndomized 2763 women Participants ranged in age from 44 to 79 years, wi th a mean age of 66.7 (SD 6.7) years. Most participants were white (89 %), married (57%), and had completed high school or some college (80%) . As expected, the prevalence of coronary risk factors was high: 62% w ere past or current smokers, 59% had hypertension, 90% had serum LDL-c holesterol of 100mg/dL or higher, and 23% had diabetes. Each woman was randomly assigned to receive one tablet containing 0.625 mg conjugate d estrogens plus 2.5 mg medroxyprogesterone acetate daily or an identi cal placebo. Participants will be evaluated every 4 months for an aver age of 4.2 years for the occurrence of CHD events (CHD death and nonfa tal myocardial infarction). We will also assess other major CHD endpoi nts, including revascularization and hospitalization for unstable angi na. The primary analysis will compare the rate of CHD events in women assigned to active treatment with the rate in those assigned to placeb o. The trial was designed to have power greater than 90% to detect a 3 5% reduction in the incidence of CHD events, assuming a 50% lag in eff ect for 2 years and a 5% annual event rate in the placebo group.