Eligibility was defined generally for all WHI components with component-specific exclusion criteria. At the time of enrollment, all women were required to be between 50 and 79 years old, postmenopausal, and intending to reside in the area for at least 3 years. Table 1 – WHI Inclusion and Exclusion Criteria in the Baseline Recruitment Monograph presents the specific criteria for the three Clinical Trial (CT) components and the Observational Study (OS).
Women interested in joining the WHI were initially screened by telephone to determine basic eligibility, followed by up to three baseline screening visits to complete the following: 1) physical measurements (height, weight, blood pressure, heart rate, waist and hip circumference), 2) collection of blood specimens (stored as serum, plasma, and buffy coat), 3) a medication / supplement inventory; and 4) questionnaires on demographic characteristics, medical history, family history, reproductive history, lifestyle/behavioral factors, and quality of life. During screening, women received information about the WHI components, and additional procedures were conducted to assess eligibility (including breast exams, food records for the Dietary Modification Trial, and a pelvic exam with endometrial aspiration and a placebo run-in for the Hormone Therapy Trials).
The WHI Clinical Trial (CT) involved three overlapping components: Dietary Modification (DM) Trial , Hormone Therapy (HT) Trials, and Calcium and Vitamin D (CaD) Trial. Women who were not willing or eligible to join the CT were invited to join the Observational Study (OS). Eligible women were allowed to join one, two, or all three clinical trials, but could not participate in both a clinical trial and the OS.
To ensure sufficient representation of all age groups, age distribution goals were specified for the CT. For HT and DM, each WHI Clinical Center had specific recruitment goals stratified by age group, study component, and, for HT, hysterectomy status. When the recruitment goal for a particular age range and trial was met, women in that age range could no longer be randomized to that trial.
The 48,835 women who joined the DM were randomly assigned to either a sustained low-fat eating pattern (40% of the women) or their usual, self-selected dietary behavior (60%). Women joining the DM could be randomized in groups of 2 to 8 women in special circumstances, such as when they lived and prepared meals together.
Women in the HT were randomized within one of two double-blind trials, Estrogen plus Progestin or Estrogen-Alone, depending on hysterectomy status at baseline. In the Estrogen plus Progestin trial, 16,608 women with an intact uterus at baseline were randomized 1:1 to take either combined Estrogen plus Progestin or placebo study pills. In the Estrogen-Alone trial, 10,739 women who were post-hysterectomy at baseline were randomized 1:1 to take either unopposed estrogen or placebo.
Women participating in either DM or HT were invited to join the CaD 12 to 24 months after randomization. The 36,282 women eligible for the double-blind CaD trial were randomized 1:1 to take study pills containing calcium/vitamin D or a placebo.
Women who were not interested or not eligible to join the CT were invited to join the OS. A total of 93,676 women were enrolled in this study.
Initial Consent to Take Part in the WHI
Hormone Therapy Consent for Women
Dietary Modification Trial Consent
Calcium/Vitamin D Trial Consent
Observational Study Consent
Supplemental Consent for Use of Stored Specimens