Special populations recruitment for the Women's Health Initiative: successes and limitations
Introduction
Clinical trials, when properly designed, conducted, analyzed, and reported, provide a valid methodology with which to compare treatments [1]. Although the clinical trial is an excellent scientific approach, the necessity of recruiting adequate numbers of participants for a clinical trial can challenge researchers [2]. Often the complexity and extent of recruitment efforts are underestimated, while the pool of eligible participants may be overestimated, thereby causing the recruitment process to take longer than initially planned [2].
Recruitment is complicated by the need to consider multiple factors, such as culture, age, gender, and socioeconomic status, when planning recruitment strategies. For ethical, social, and scientific reasons, longitudinal prevention trials require the recruitment and retention of subjects from a number of diverse population groups [3], [4]. Difficulties inherent to the recruitment process may be compounded when trials must enlist participants from previously underrepresented populations or from populations that may be suspicious of clinical research (i.e., low-income and/or minority populations) [4]. Minority populations (i.e., groups defined by race, socioeconomics, geography, ethnicity, culture, or gender) may be more apprehensive about participation in clinical trials and may have interests that conflict with clinical trial objectives [3]. Historically, these groups have limited experience with clinical research and may be more likely to be wary of such research due to past abuses of vulnerable populations.
The paucity of research on older and ethnic minority adults has prompted many organizations to ask researchers to include more older ethnic minority adults in their studies [5], [6]. However, recruiting older adults has been considered to be especially difficult, time-consuming, and expensive [6]. The recruitment of older women, particularly older minority women, demands strategies that are responsive to cultural nuances of age and ethnicity [5], [7]. Researchers recognize that there is no one-size-fits-all recruitment plan. Marketing and public relations strategies based upon scientific evidence are essential for the effective recruitment of previously underrepresented groups.
The Women's Health Initiative (WHI) is a study designed to investigate the major causes of death and disability in postmenopausal women (i.e., cardiovascular disease, cancer, and osteoporosis). The two main study arms of WHI are a randomized Clinical Trial (CT) and an Observational Study (OS). The CT has three components: the Dietary Modification (DM) component which examines the effects of a low-fat diet on prevention of cancer and heart disease; the Hormone-Replacement Therapy (HRT) component which assesses the benefits and risks of hormone-replacement therapy; and the Calcium and Vitamin D (CAD) component which assesses the effects of calcium and vitamin D supplements in preventing osteoporosis and colon cancer. The OS examines the predictors and biological markers of diseases, such as cancer, cardiovascular disease, and fractures.
Nationwide WHI recruitment began in 1993 with follow-up for 8 to 12 years. The recruitment goals of WHI were ambitious. The CT was to randomize 64,500 postmenopausal women, and the OS was to enroll 100,000 women between the ages of 50–79 years. It was expected that 20% of the enrolled study participants in both the CT and OS would come from minority populations. With projected study sample of 164,500 women of varying ethnic and socioeconomic backgrounds, WHI is perhaps one of the most challenging recruitment efforts ever undertaken.
This paper describes both study-wide recruitment methods as well as site-specific efforts used to recruit minority populations into the DM and HRT components of the clinical trial arm of WHI. Based on the original design of WHI, the Calcium and Vitamin D (CAD) component was offered to enrolled participants after 1 year of being in the WHI study. In addition, since the designs of clinical trials and observational studies are very different, and as are the issues (barriers and motivations) surrounding recruitment challenges, this manuscript will focus only on the WHI recruitment experience in the CT arm only.
The various strategies used to recruit women into the DM and HRT component of the CT arm will be described, and successes and limitations will be noted. Based on the recruitment experiences of WHI researchers, a number of recommendations will be made concerning effective recruitment strategies, which are specific to ethnicity and other demographic characteristics.
Section snippets
Methods
The Women's Health Initiative established 40 clinical centers throughout the United States, with a Coordinating Center in Seattle, Washington (see Map for clinic locations in Fig. 1). Each center had an average recruitment goal of 1500 women for the DM and HRT components of CT and 2,200 women for the OS, with goals for some individual clinics increased by 25–75%. Ten clinical centers were designated as minority recruitment centers on the basis of proposals demonstrating their history of
Results
Overall recruitment efforts across the 40 WHI clinic centers resulted in the enrollment of 161,856 participants, of which 17.5% were minority women. A total of 68,135 women were randomized in the Clinical Trial arm of which 18.5% were minority women, and 93,721 were enrolled in the Observational Study arm of which 16.7% were minority women (Table 1).
Within the CT arm, WHI achieved 101.7% of the DM goal of 48,000 participants and 99.4% of the HRT goal of 27,500. With 18.5% of participants from
Results of recruitment survey per recruitment coordinators
Of the 40 clinical centers, 39 returned the survey describing and assessing recruitment strategies. One minority clinical center did not report. Recruitment coordinators at the centers responded to four main items: (1) main recruitment strategies used; (2) most effective strategies, (3) least effective strategies; and (4) additional needs that could have enhanced recruitment.
Discussion
An important step in assuring that results from a clinical trial are generalizable is recruitment and enrollment of members of various ethnic minority populations into the trial. With the introduction of the NIH Revitalization Act, trialists expressed concerns about effective [9] and efficient [10], [11] recruitment of minority subjects, often considered to be “hard-to-reach” populations [2]. As investigators strive to diversify the sample populations that are being recruited to participate in
Acknowledgements
The research upon which this publication is based was performed pursuant to Contract No. N01-WH32105 with the National Institutes of Health.
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