The women's health initiative recruitment methods and results

https://doi.org/10.1016/S1047-2797(03)00042-5Get rights and content

Introduction

One of the most challenging aspects of the Women's Health Initiative (WHI) was the recruitment of more than 161,000 women for this long-term prevention trial and observational study. The WHI had many enrollment goals that made recruitment efforts formidable (1). These included the recruitment of postmenopausal women, a group seldom targeted for clinical trials; enrolling minority groups in at least the same proportion as they existed in the general population; and enrolling women willing to participate in a long-term (8–12 year) study. The success of the WHI in meeting these goals can be attributed to several factors: the experience gained from prior studies, such as the National Cancer Institute (NCI)-sponsored Women's Health Trial (2), the subsequent Women's Health Trial Feasibility Study in Minority Populations (3), and the Postmenopausal Estrogen/Progestin Interventions Trial (4); detailed planning by the WHI investigators; the dedication of recruiters, staff, and investigators at the clinical centers; and, a social and political climate that enhanced women's interest in health research.

Prior to the WHI, few large-scale prevention or clinical trials focused on postmenopausal women. Indeed, until recently, relatively little emphasis was placed on the recruitment of women of any age into such studies (5). However, during the last decade, a number of forces have come together to change this situation. The stance that women should be “protected” from biomedical research 6., 7. has given way to the requirement that they be included so that more can be learned about their health care needs (8).

Likewise, there have been increased efforts to recruit members of racial/ethnic minorities into clinical and prevention trials. The barriers that have limited the participation of minorities in biomedical research have been reviewed in detail elsewhere 9., 10., 11.. To ensure that the WHI findings would be as generalizable as possible to U.S. postmenopausal women, the study had to find ways to overcome these barriers and recruit a representative sample of minority women in this age group.

This article reviews the WHI study population and screening process, recruitment methods, and the results of the recruitment efforts. We describe the common and unique strategies developed by individual clinics to enroll women in their local communities and the national framework that supported these efforts. The implications of the success of these methods for future studies are also discussed.

Section snippets

Study population

Eligibility was defined generally for all WHI components with component-specific exclusion criteria. All women enrolled in the WHI were between 50 and 79 years old and were postmenopausal at the time of enrollment. Inclusion criteria were liberal in order to facilitate recruitment and enhance generalizability. In addition to age and menopausal status, eligibility criteria for the clinical trial (CT) and observational study (OS) included ability and willingness to provide written informed

Clinical centers

Participants were recruited from areas surrounding forty clinical centers established primarily at major academic health centers in 24 states and the District of Columbia. (See the appendix in Rossouw's article for a list of clinical center locations.) Recruitment areas included urban, suburban, and rural populations. The original plan anticipated 45 clinical centers, each of which was to enroll 1,267 trial participants and 2,222 OS participants (total clinical trial = 57,000; OS = 100,000). Only

Overview of the recruitment and screening protocol

For most clinics, initial contact with potential participants was through a mass mailing of the recruitment brochure, which provided basic information on the WHI and contained a postage-paid return postcard to indicate interest in study participation. Trained telephone interviewers conducted additional eligibility screening with age-eligible women who returned cards or called the clinical center. A total of three clinic visits were conducted to enroll women in the clinical trial and at least

Local clinical center activities

The responsibility for recruitment rested in the hands of the individual clinical centers. Each was given the latitude to determine their own recruitment strategies, staffing patterns, clinic configuration, and visit flow. This level of flexibility was intended to allow each clinic to adapt the protocol to local strengths and constraints.

Results

The number of women with WHI screening data and the proportion of those randomized or enrolled in the clinical trial and OS by age and ethnic group are provided in Table 2. A total of 373,092 women completed the initial screening form. Of those, 68,133 (18%) went through the subsequent screening visits to be randomized into the clinical trial, and 93,676 (25%) were enrolled in the OS. Women in the oldest age group (70–79 years of age) had the lowest proportion of women randomized to the

Discussion

The WHI met recruitment goals, including reaching a diverse population of postmenopausal women. The recruitment experience of the WHI may provide several useful lessons for investigators undertaking randomized clinical trials with older women.

At the clinic level, several factors may have contributed to successful recruitment. First, making the clinic as accessible as possible to older women was crucial. For many clinics, this involved staffing a satellite clinic part- or full-time and providing

Summary

The recruitment of women into the WHI stands as an important accomplishment in clinical research history. This study demonstrated that postmenopausal women of varied ethnic groups could be recruited in large numbers across the U.S. More than 161,000 enrolled in one or more components of the study. The complex study design included three nested clinical trials and an observational study, and allowed each woman to choose how she participated, from taking study pills to enrolling in a dietary

First page preview

First page preview
Click to open first page preview

References (16)

There are more references available in the full text version of this article.

Cited by (622)

View all citing articles on Scopus
View full text