An Assessment of the NIH Women's Health Initiative (1993) / Chapter Skim
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Executive Summary
Executive Summary
Pages 1-18
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The WHI will investigate strategies for preventing three of the leading causes of death and decreased quality of life for older women—cardiovascular disease, breast cancer, and osteoporotic fractures. But while recruitment of study participants has already begun, serious questions remain about the design, timetable, and likely results of this $625 million public investment.
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Secondary hypothesis: A low fat dietary pattern reduces the risk of coronary heart disease. Hormone Replacement Therapy (HRT)
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Cost estimates could be exquisitely accurate yet not be justified by the results if the structure of the study design were flawed to the extent that it could not answer the study questions. Hence, the TOM committee considered it within its charge to address question 2 to review the study design and statistical methods proposed by NTH.
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were reviewed at one time or another (e.g., the dietary modification triad was reviewed multiple times in earlier proposals, none of which were allowed to proceed) , the committee's impression is that the complicated interlocking combination of the clinical trial and the observational study was not reviewed as rigorously as the usual Institute-initiated project.
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Sample Characterzsfics In determining sample size, the study design relies heavily on extremely uncertain assumptions regarding magnitude of effect and lag times. This concern is a factor in the recommendation described below regarding study duration.
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Specificity of Intervention and Elect The CI' design does not distinguish which element of the low fat dietary pattern may be responsible for any observed outcome. Similarly, the design mIl not allow analyses to distinguish whether calcium or calcium plus vitamin D is responsible for any observed Outcome.
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The committee has identified five operational issues that could jeopardize the success of the study: Recruilment, Retention, and Adherence The message of the study is not adequately developed and may be misleading. · The committee suggests that NIH and the clinical centers develop an overall message for the study that pays particular attention to long-tem~ recruitment strategies for older and minority participants, and does not emphasize the WH!
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This reliance on institutional support may be reasonable in the case of the Vanguard Clinical Centers, but the committee felt it is unlikely that an additional 29 institutions can be identified that have both the experience to carry out the tasks of high quality research and the ability to provide additional resources. Potential sources of budget shortfall include lagging participant recruitment, which could require increased staff resources; staff turnover, which could require training and travel resources and might delay recruitment, threaten adherence, and, therefore, affect study validity; and cross-over of participants between study intervention regimens and control status.
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The committee suggested that the following issues be highlighted in the development of the CPS protocol: · project selection should ensure that components are suitable for incorporation into comprehensive community-based programs; · projects should attempt to decrease unfavorable disparities between lower SES and racial/ethnic minority women and higher SES nonminonty women and to promote the creation of culturally appropriate strategies at low cost; · projects should include strong training components (that will permit personnel to train others in additional communities) , possibly resulting in a set of regional training centers; · projects should employ many process measures needed for cost-effectiveness analyses; and
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· The committee recommends that the dietary modification-breast cancer hypothesis be considered a subsidiary rather than a primary hypothesis, shifting the emphasis to the effect of dietary modification on coronary heart disease outcomes. making those the primary hypotheses.
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This timeframe does not allow for adequate follow-up for the DM and breast cancer hypothesis, the DM and colorectal cancer hypothesis, or the HRT and breast cancer hypothesis. However, the committee feels that, as currently designed, the CT does not have a high probability of Belying statistically significant results for the DM and breast cancer hypothesis or the HRT and breast cancer hypothesis, even after more prolonged follow-up.
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Community Prevention Study · The development of the Community Prevention Study is of equal importance to the CT and the OS. It urgently needs a more definitive plan and the committee recommends that NIH develop one quickly.
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Is the size of the study population appropriate? The methodologies selected a clinical trial, an observational study, and community studies are appropriate for the study of the efficacy or effectiveness of certain interventions to improve women's health, for generating further hypotheses, and for implementing and evaluating community intervention strategies.
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Three primary hypotheses are the basis of the CT: · A low fat dietary pattern will reduce the incidence of breast cancer and colorectal cancer; · Hormone replacement therapy will reduce the incidence of cardiovascular disease; and · Calcium and vitamin D supplements will reduce the incidence of osteoporotic hip fracture. The design of the trial, the number of women who will participate, and the methods used to determine health status all flow from these hypotheses.
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NTH and Vanguard Clinical Center representatives have indicated that the additional funds necessary for successful completion of the trial will be covered by the institutions in which the Vanguard Clinical Centers are based. This reliance on institutional support may be reasonable in the case of the Vanguard Clinical Centers, but the committee felt it is unlikely that an additional 29 institutions can be identified that have both the experience to carry out the tasks of high quality research and the ability to provide additional resources.
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16 AN ASSESSMENT OF THE NIH WOMEN'S HEALTH INITIATIVE of effects on the risk of coronary heart disease. Moreover, NIH will need to consider whether the study objectives that can be achieved in the modified study are worth the investment.
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