Approached to monitoring the results of long-term disease prevention trials: examples from the Women's Health Initiative

Menopausal hormone therapy and change in physical activity in the Women's Health Initiative hormone therapy clinical trials

OBJECTIVE

The menopausal transition results in a progressive decrease in circulating estrogen levels. Experimental evidence in rodents has indicated that estrogen depletion leads to a reduction of energy expenditure and physical activity. It is unclear whether treatment with estrogen therapy increases physical activity level in postmenopausal women.

METHODS

A total of 27,327 postmenopausal women aged 50-79 years enrolled in the Women's Health Initiative randomized double-blind trials of menopausal hormone therapy. Self-reported leisure-time physical activity at baseline, and years 1, 3, and 6 was quantified as metabolic equivalents (MET)-h/wk. In each trial, comparison between intervention and placebo groups of changes in physical activity levels from baseline to follow-up assessment was examined using linear regression models.

RESULTS

In the CEE-alone trial, the increase in MET-h/wk was greater in the placebo group compared with the intervention group at years 3 ( P = 0.002) and 6 ( P < 0.001). Similar results were observed when analyses were restricted to women who maintained an adherence rate ≥80% during the trial or who were physically active at baseline. In the CEE + MPA trial, the primary analyses did not show significant differences between groups, but the increase of MET-h/wk was greater in the placebo group compared with the intervention group at year 3 ( P = 0.004) among women with an adherence rate ≥80%.

CONCLUSIONS

The results from this clinical trial do not support the hypothesis that estrogen treatment increases physical activity among postmenopausal women.

The Need for Combined Assessment of Multiple Outcomes in Noninferiority Trials in Oncology

Noninferiority trials in oncology assess novel therapies with the potential for slightly worse recurrence or death outcomes (ie, the margin of noninferiority) than standard therapies. This poses a dilemma because, in the absence of potential health outcome advantages, these trials may not provide the treatment equipoise required for an ethical study. Any new treatment with the potential for slightly worse recurrence or death outcomes should have countervailing health outcome advantages, but these are rarely taken into account in the design of noninferiority trials. This article presents the argument that not only the potentially worse health outcomes but also the potential benefits of the novel therapy should be considered when designing, analyzing, and reporting noninferiority trials. Some approaches to study design and analysis that consider both primary and secondary end points are discussed, and reporting the joint distributions of end points for the novel and standard treatments is recommended.

Exact sequential analysis for multiple weighted binomial end points

Sequential analysis is used in clinical trials and postmarket drug safety surveillance to prospectively monitor efficacy and safety to quickly detect benefits and problems, while taking the multiple testing of repeated analyses into account. When there are multiple outcomes, each one may be given a weight corresponding to its severity. This paper introduces an exact sequential analysis procedure for multiple weighted binomial end points; the analysis incorporates a drug's combined benefit and safety profile. It works with a variety of alpha spending functions for continuous, group, or mixed group-continuous sequential analysis. The binomial probabilities may vary over time and do not need to be known a priori. The new method was implemented in the free R Sequential package for both one- and two-tailed sequential analysis. An example is given examining myocardial infarction and major bleeding events in patients who initiated non-steroidal antiinflammatory drugs.

Use of composite outcomes to assess risk-benefit in clinical trials

Before a novel treatment can be deemed a clinical success, an assessment of its risk-benefit profile must be made. One of the inherent challenges for this assessment comes from the multiplicity that arises from comparing treatment groups across multiple outcomes. Composite outcomes that summarize a patient's clinical status, or severity, across a prioritized list of safety and efficacy outcomes have become increasing popular. In this article, we review these approaches and illustrate through examples some of the challenges and complexities of a composite derived from prioritized outcomes, such as the win ratio. These challenges include the difficult tension between the analytical validity that comes from choosing a pre-specified outcome and an evaluation that is responsive to unexpected safety events that arise during the course of a trial. Other challenges include a sensitivity of the resulting test statistic to the underlying censoring distribution and other nuisance parameters. Approaches that resolve some of the difficulties of the analytical challenges associated with prioritized outcomes are then discussed. Ultimately, a composite outcome of net clinical benefit is another decision tool, but one to be used alongside more traditional analyses of efficacy and safety, and with the broader perspective that investigators, the data safety monitoring board, and regulators bring to an evaluation of risk-benefit.

Where's the utility in Bayesian data-monitoring of clinical trials?

Background Data monitoring is now an established part of good practice in clinical trials. Bayesian procedures for data-monitoring of treatment trials have been proposed and used, but sometimes without explicit consideration of utilities. A natural statistical framework for evidence-based medicine is a Bayesian approach to decision-making that incorporates an integrated summary of the available evidence and associated uncertainty with assessment of utilities.

Methods We explore this approach to data monitoring, explicitly addressing separately the individual, scientific and public health perspectives. The Data Monitoring Committee's decision can then be thought of as a weighted combination of these perspectives. These ideas are illustrated with a trial of treatments for oesophageal cancer.

Results For a Bayesian approach without explicit utilities we show that a utility structure is, in fact, implicit, and that it may be viewed as a weighted sum of the individual and scientific utilities.

Conclusions We argue that explicit consideration of utilities leads to decisionmaking that is more transparent, and lays foundations for data monitoring of more complex trials.

Systematic qualitative review of the literature on data monitoring committees for randomized controlled trials

Aims To systematically review the published literature on data monitoring committees (DMCs) for randomized controlled trials (RCT) and summarize information and opinions on best practice. This was part of the DAMOCLES project. Methods A systematic and comprehensive search of five online bibliographic databases was performed, identifying 4007 potentially relevant articles. These were assessed in two stages by the authors. The 84 most relevant articles were agreed and were supplemented with extracts from 16 books: ultimately, 100 sources were reviewed. A series of 23 questions plus subquestions were developed to structure the data extraction and interpretation process.

Results Much has been written about DMCs but by a rather small community of authors. The papers included some results of surveys, but were mainly opinion pieces based on the authors' beliefs, practices and experiences. There is a lack of empirical evidence for many aspects of DMCs. There was a great range of detail in the literature relating to the prespecified questions. It was generally agreed that interim monitoring of accumulating data was necessary in some form for most trials. Questions such as membership of the DMC featured widely in the literature with opinions and practice ranging from 3–20 members, of whom between none and all should be independent. There was a consensus that formal statistical methods should be used as tools to guide decision making rather than as hard rules. Conversely, topics such as the training and experience required for DMC membership were discussed in very few papers.

Conclusions There is a consensus in the published literature in a number of areas, although there are many different models for structure and functions of a DMC. While uncertainty remains about some issues, it is strongly recommended that an explicit set of guidelines (Charter) is prepared for each DMC prior to the start of the trial specifying clearly how it will operate.

A decision rule for sequential monitoring of clinical trials with a primary and supportive outcome

Background Many clinical trials have multiple outcomes. Formal interim monitoring guidelines that take account of multiple outcomes can be useful to Data Monitoring Committees (DMC). Previous research has focused on marginal criteria that control the overall type I error for bivariate endpoints corresponding to efficacy and safety. Usually, an `or' decision rule is used, that is, the trial is stopped when either the safety or the efficacy endpoint crosses a boundary.

Purpose In many trials there is not a clear difference between what is considered a safety and an efficacy endpoint. Likewise, in some studies there is interest in more than one disease outcome and while there may be a primary efficacy endpoint, interim monitoring might also involve a measure of overall health. For these situations, an `and' decision rule might be more appropriate; that is, the trial is stopped only when both endpoints cross a boundary. Formulation of this new decision rule at the design stage would encourage more discussion among trial investigators of monitoring guidelines and would result in improved guidelines for DMCs.

Methods In this paper, we propose stopping guidelines for such trials with two major outcomes that control the overall type I error and stop early only if both endpoints indicate superiority for the same treatment. Trials with two treatments are considered and we develop sets of paired two-sided boundaries, permitting one endpoint to be primary and the other supportive, with or without pre-specifying which one is primary.

Results The results show that the boundaries depend on the correlation between the two outcomes. The critical values increase as the correlation increases in most cases. For low to moderate correlation and before the last stage, critical values based on the O'Brien Fleming (or Pocock) error spending function that consider the correlation are lower than those which do not.

Limitations Investigators might not want to stop a trial early with the small size of the critical values that result from this decision rule for some situations. For a trial in which the treatment effect for one outcome is large, while for the other it is small, the proposed decision rule has low power to accept this treatment for its superiority on both outcomes. Also, we do not provide a separate P-value for each outcome since type I error is not controlled for individual null hypotheses.

Conclusions For trials involving two major health outcomes these stopping guidelines may be appropriate for DMCs when the trial investigators and sponsor recommend that early termination not be considered unless the findings are consistent for both outcomes. Clinical Trials 2007; 4: 140—153. http://ctj.sagepub.com

Utility-based designs for randomized comparative trials with categorical outcomes

A general utility-based testing methodology for design and conduct of randomized comparative clinical trials with categorical outcomes is presented. Numerical utilities of all elementary events are elicited to quantify their desirabilities. These numerical values are used to map the categorical outcome probability vector of each treatment to a mean utility, which is used as a one-dimensional criterion for constructing comparative tests. Bayesian tests are presented, including fixed sample and group sequential procedures, assuming Dirichlet-multinomial models for the priors and likelihoods. Guidelines are provided for establishing priors, eliciting utilities, and specifying hypotheses. Efficient posterior computation is discussed, and algorithms are provided for jointly calibrating test cutoffs and sample size to control overall type I error and achieve specified power. Asymptotic approximations for the power curve are used to initialize the algorithms. The methodology is applied to re-design a completed trial that compared two chemotherapy regimens for chronic lymphocytic leukemia, in which an ordinal efficacy outcome was dichotomized, and toxicity was ignored to construct the trial's design. The Bayesian tests also are illustrated by several types of categorical outcomes arising in common clinical settings. Freely available computer software for implementation is provided. Copyright © 2016 John Wiley & Sons, Ltd.

A rank test for bivariate time-to-event outcomes when one event is a surrogate

In many clinical settings, improving patient survival is of interest but a practical surrogate, such as time to disease progression, is instead used as a clinical trial's primary endpoint. A time-to-first endpoint (e.g., death or disease progression) is commonly analyzed but may not be adequate to summarize patient outcomes if a subsequent event contains important additional information. We consider a surrogate outcome very generally as one correlated with the true endpoint of interest. Settings of interest include those where the surrogate indicates a beneficial outcome so that the usual time-to-first endpoint of death or surrogate event is nonsensical. We present a new two-sample test for bivariate, interval-censored time-to-event data, where one endpoint is a surrogate for the second, less frequently observed endpoint of true interest. This test examines whether patient groups have equal clinical severity. If the true endpoint rarely occurs, the proposed test acts like a weighted logrank test on the surrogate; if it occurs for most individuals, then our test acts like a weighted logrank test on the true endpoint. If the surrogate is a useful statistical surrogate, our test can have better power than tests based on the surrogate that naively handles the true endpoint. In settings where the surrogate is not valid (treatment affects the surrogate but not the true endpoint), our test incorporates the information regarding the lack of treatment effect from the observed true endpoints and hence is expected to have a dampened treatment effect compared with tests based on the surrogate alone. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Evidence selection for a prescription drug's benefit-harm assessment: challenges and recommendations

OBJECTIVES

To describe challenges and make recommendations for researchers in how they select evidence to quantitatively assess a prescription drug's benefits and harms.

STUDY DESIGN AND SETTING

These challenges and recommendations are based on our recent experience conducting a benefit-harm assessment for the prescription drug roflumilast. We considered the selection of evidence to quantify (1) the drug's treatment effects in patients, (2) the patient population's baseline risks for beneficial and harmful outcomes without treatment, and (3) the patient population's preferences for these beneficial effects and harms. These are fundamental steps for most benefit-harm assessment methods.

RESULTS

We identify critical issues in selecting evidence for each of these steps. We justify in particular the need to incorporate (1) clinical trials for the drug's specific treatment effect; (2) observational studies with the most valid, precise, and applicable effect estimates for the baseline risk; and (3) flexible weighting approaches for balancing the drug benefits and harms.

CONCLUSION

We identify challenges and make recommendations for selecting evidence at the critical steps in a prescription drug's benefit-harm assessment. Our findings should assist other researchers conducting these assessments for prescription drugs, which could help regulators, medical professionals, and patients make better decisions about prescription drug use.

Cancer incidence and mortality during the intervention and postintervention periods of the Women's Health Initiative dietary modification trial

BACKGROUND

The Women's Health Initiative (WHI) low-fat (20% kcal) dietary modification (DM) trial (1993-2005) demonstrated a nonsignificant reduction in breast cancer, a nominally significant reduction in ovarian cancer, and no effect on other cancers (mean 8.3 years intervention). Consent to nonintervention follow-up was 83% (n = 37,858). This analysis was designed to assess postintervention cancer risk in women randomized to the low-fat diet (40%) versus usual diet comparison (60%).

METHODS

Randomized, controlled low-fat diet intervention for prevention of breast and colorectal cancers conducted in 48,835 postmenopausal U.S. women, ages 50 to 79 years at 40 U.S. sites. Outcomes included total invasive cancer, breast cancer, and colorectal cancer, and cancer-specific and overall mortality.

RESULTS

There were no intervention effects on invasive breast or colorectal cancer, other cancers, or cancer-specific or overall mortality during the postintervention period or the combined intervention and follow-up periods. For invasive breast cancer, the hazard ratios (HR) and 95% confidence interval (CI) were 0.92 (0.84-1.01) during intervention, 1.08 (0.94-1.24) during the postintervention period, and 0.97 (0.89-1.05) during cumulative follow-up. A reduced risk for estrogen receptor positive/progesterone receptor-negative tumors was demonstrated during follow-up. In women with higher baseline fat intake (quartile), point estimates of breast cancer risk were HR, 0.76 (95% CI, 0.62-0.92) during intervention versus HR, 1.11 (95% CI, 0.84-1.4) during postintervention follow-up (Pdiff = 0.03).

CONCLUSIONS

Dietary fat intake increased postintervention in intervention women; no long-term reduction in cancer risk or mortality was shown in the WHI DM trial.

IMPACT

Dietary advisement to reduce fat for cancer prevention after menopause generally was not supported by the WHI DM trial.

Using multiple risk models with preventive interventions

An ideal preventive intervention would have negligible side effects and could be applied to the entire population, thus achieving maximal preventive impact. Unfortunately, many interventions have adverse effects and beneficial effects. For example, tamoxifen reduces the risk of breast cancer by about 50% and the risk of hip fracture by 45%, but increases the risk of stroke by about 60%; other serious adverse effects include endometrial cancer and pulmonary embolus. Hence, tamoxifen should only be given to the subset of the population with high enough risks of breast cancer and hip fracture such that the preventive benefits outweigh the risks. Recommendations for preventive use of tamoxifen have been based primarily on breast cancer risk. Age-specific and race-specific rates were considered for other health outcomes, but not risk models. In this paper, we investigate the extent to which modeling not only the risk of breast cancer, but also the risk of stroke, can improve the decision to take tamoxifen. These calculations also give insight into the relative benefits of improving the discriminatory accuracy of such risk models versus improving the preventive effectiveness or reducing the adverse risks of the intervention. Depending on the discriminatory accuracies of the risk models, there may be considerable advantage to modeling the risks of more than one health outcome.

Physical activity, weight control, and breast cancer risk and survival: clinical trial rationale and design considerations

Substantial observational epidemiological evidence exists that physical activity and weight control are associated with decreased risk of postmenopausal breast cancer. Uncertainty remains regarding several aspects of these associations, including the effect of possible confounding factors on these associations. We present the rationale and design for two randomized controlled trials that can help resolve this uncertainty. In a 5-year prevention trial conducted among women at high risk of breast cancer, the primary endpoint would be breast cancer incidence. For a comparable survivorship trial, the primary endpoint would be the disease-free interval and secondary endpoints would be breast cancer recurrence-free interval, second primary breast cancer, and total invasive plus in situ breast cancer. A set of inclusion and exclusion criteria is proposed for both trials. Intervention goals are the same for both trials. Goals for the weight control intervention would be, for women whose body mass index (BMI) is greater than 25 kg/m(2), to lose 10% of body weight and, for women whose BMI is less than or equal to 25 kg/m(2), to avoid weight gain. The goal for the physical activity intervention would be to achieve and maintain regular participation in a moderate-intensity physical activity program for a total of 150-225 minutes over at least 5 days per week. Sample size calculations are based on alternative assumptions about hazard ratio, adherence, follow-up duration, and power and are presented for the primary prevention and survivorship trials. Although both studies could enhance our understanding of breast cancer etiology and benefit public health, practical considerations, including smaller sample size, ease of recruitment, and reduced likelihood of early termination, favor the survivorship trial at this time.

Monitoring and reporting of the Women's Health Initiative randomized hormone therapy trials

BACKGROUND

The Women's Health Initiative (WHI) randomized trial of estrogen plus progestin (E + P) was terminated early based on an assessment of harms exceeding benefits for disease prevention. The results contravened prevailing wisdom and a large body of literature regarding benefits of menopausal hormone therapy. The results and their interpretation have been the subject of considerable debate.

PURPOSE/METHODS

To describe the process of developing a trial monitoring plan, the key interim and final data, and to explain the choice of statistical methods used in trial monitoring and reporting.

RESULTS

A formalized monitoring plan was developed using statistical methods that acknowledged protocol-defined design and analysis plans, input of monitoring board members especially regarding the role of various study outcomes, and multiple comparisons. Major early departures from design assumptions concerning treatment effects indicated a need for additional flexibility in safety monitoring. When the trials were stopped early, questions arose as to how closely the statistical methods in published reports should correspond to those defined by protocol or used in monitoring.

METHODS

were selected to provide a simple and transparent summary of the primary results, with a cautious interpretation promoted by acknowledgement of multiple testing.

CONCLUSIONS

Developing a formal trial monitoring plan with a view towards influencing clinical practice is useful for creating consensus among DSMB members regarding the evidence that would justify stopping a trial and the framework to be used to address statistical complexities. Departures from design assumptions typically occur. These reinforce the role of the DSMB in exercising their judgment, and the judicious adaptation of these statistical guidelines in monitoring and reporting trials. In communicating the results in such circumstances, priority should be given to presenting as fair, accurate and transparent a view of the data and findings as current methods and technology allow.

Monitoring the randomized trials of the Women's Health Initiative: the experience of the Data and Safety Monitoring Board

Data Safety Monitoring Committees (DSMB) for large, long-term randomized trials of agents in common use face challenging problems especially when the emerging data indicate unanticipated effects. The DSMB for the Women's Health Initiative Clinical Trials, on observing early indication of a surprising adverse cardiovascular effect of post-menopausal hormones, spent several years deliberating what recommendations it should make. This paper describes the dilemmas faced by the DSMB and the considerations it made over the course of its existence. The paper concludes with some recommendations for other DSMBs.

Statistical issues arising in the Women's Health Initiative

A brief overview of the design of the Women's Health Initiative (WHI) clinical trial and observational study is provided along with a summary of results from the postmenopausal hormone therapy clinical trial components. Since its inception in 1992, the WHI has encountered a number of statistical issues where further methodology developments are needed. These include measurement error modeling and analysis procedures for dietary and physical activity assessment; clinical trial monitoring methods when treatments may affect multiple clinical outcomes, either beneficially or adversely; study design and analysis procedures for high-dimensional genomic and proteomic data; and failure time data analysis procedures when treatment group hazard ratios are time dependent. This final topic seems important in resolving the discrepancy between WHI clinical trial and observational study results on postmenopausal hormone therapy and cardiovascular disease.

Tamoxifen for the prevention of breast cancer: current status of the National Surgical Adjuvant Breast and Bowel Project P-1 study

BACKGROUND

Initial findings from the National Surgical Adjuvant Breast and Bowel Project Breast Cancer Prevention Trial (P-1) demonstrated that tamoxifen reduced the risk of estrogen receptor-positive tumors and osteoporotic fractures in women at increased risk for breast cancer. Side effects of varying clinical significance were observed. The trial was unblinded because of the positive results, and follow-up continued. This report updates our initial findings.

METHODS

Women (n = 13,388) were randomly assigned to receive placebo or tamoxifen for 5 years. Rates of breast cancer and other events were compared by the use of risk ratios (RRs) and 95% confidence intervals (CIs). Estimates of the net benefit from 5 years of tamoxifen therapy were compared by age, race, and categories of predicted breast cancer risk. Statistical tests were two-sided.

RESULTS

After 7 years of follow-up, the cumulative rate of invasive breast cancer was reduced from 42.5 per 1000 women in the placebo group to 24.8 per 1000 women in the tamoxifen group (RR = 0.57, 95% CI = 0.46 to 0.70) and the cumulative rate of noninvasive breast cancer was reduced from 15.8 per 1000 women in the placebo group to 10.2 per 1000 women in the tamoxifen group (RR = 0.63, 95% CI = 0.45 to 0.89). These reductions were similar to those seen in the initial report. Tamoxifen led to a 32% reduction in osteoporotic fractures (RR = 0.68, 95% CI = 0.51 to 0.92). Relative risks of stroke, deep-vein thrombosis, and cataracts (which increased with tamoxifen) and of ischemic heart disease and death (which were not changed with tamoxifen) were also similar to those initially reported. Risks of pulmonary embolism were approximately 11% lower than in the original report, and risks of endometrial cancer were about 29% higher, but these differences were not statistically significant. The net benefit achieved with tamoxifen varied according to age, race, and level of breast cancer risk.

CONCLUSIONS

Despite the potential bias caused by the unblinding of the P-1 trial, the magnitudes of all beneficial and undesirable treatment effects of tamoxifen were similar to those initially reported, with notable reductions in breast cancer and increased risks of thromboembolic events and endometrial cancer. Readily identifiable subsets of individuals comprising 2.5 million women could derive a net benefit from the drug.

Data and Safety Monitoring in Clinical Research: A National Institute of Neurologic Disorders and Stroke Perspective

The National Institute of Neurologic Disorders and Stroke supports a broad spectrum of research in the diagnosis and treatment of neurologic disease. Emergency medicine is increasingly involved in clinical research for patients with neurologic emergencies. Independent data and safety monitoring are critical components of clinical trials to ensure the protection of patients and the scientific integrity of the research. We review National Institute of Neurologic Disorders and Stroke principles of data and safety monitoring and provide examples to illustrate key concepts.

Risk-benefit profile for raloxifene: 4-year data From the Multiple Outcomes of Raloxifene Evaluation (MORE) randomized trial

Posthoc analysis of the MORE osteoporosis treatment trial assessed risk-benefit profile of raloxifene in 7705 postmenopausal women. A major disease outcomes global index resulted in annual rates of 1.39% and 1.83% in the raloxifene and placebo groups, respectively (HR, 0.75; 95% CI, 0.62-0.92), compatible with a favorable risk-benefit profile for raloxifene for treating postmenopausal osteoporosis.

INTRODUCTION

The Women's Health Initiative (WHI) trial reported overall risks that exceeded benefits from use of estrogen-progestin in healthy postmenopausal women. The objective of this posthoc analysis of the Multiple Outcomes of Raloxifene Evaluation (MORE) trial was to assess the safety profile of raloxifene, a selective estrogen receptor modulator indicated for the prevention and treatment of osteoporosis, using the global index method from the WHI trial.

MATERIALS AND METHODS

A total of 7705 postmenopausal women (mean age, 67 years) were enrolled in the MORE osteoporosis treatment trial and randomly assigned to receive placebo or one of two doses of raloxifene (60 or 120 mg/day) for 4 years. A global index of clinical outcomes, defined as described for the WHI trial (the earliest occurrence of coronary heart disease, stroke, pulmonary embolism, invasive breast cancer, endometrial cancer, colorectal cancer, hip fracture, or death because of other causes) was applied to the MORE trial data. Physicians blinded to treatment assignment adjudicated events. Intention-to-treat survival analysis of time-to-first-event was performed using a proportional hazards model.

RESULTS AND CONCLUSIONS

The annualized rate of global index events was 1.83% in the placebo group and 1.39% in the combined raloxifene dose groups (hazard ratio [HR], 0.75; 95% CI, 0.62-0.92). Analyzing individual dose groups separately yielded the same results (HR for 60 mg/day, 0.75; 95% CI, 0.60-0.96: HR for 120 mg/day, 0.75; 95% CI, 0.59-0.95). Subgroup analyses showed no significant interactions between age or hysterectomy status and the effect of raloxifene on the global index (interaction p > 0.1), whereas the global index risk reduction seemed to be greater in obese women compared with nonobese women (interaction p = 0.03). The significant 25% reduction in global index is compatible with a favorable risk-benefit safety profile when raloxifene is used for osteoporosis treatment in postmenopausal women. These results require confirmation in ongoing clinical trials.

How does the WHI study alter the risk–benefit ratio of HT?

Good clinical practice depends on knowledge of the current best medical care research evidence, but clinicians must be able to determine what is the best evidence and whether this evidence is relevant to their own patients. At the heart of evidence-based medicine is the assessment of the validity, importance, and relevance of a given study. These may be evaluated by asking key questions; here these questions are applied to the WHI study.

Research staff turnover and participant adherence in the Women's Health Initiative

Maintaining participant adherence is a prerequisite for successful completion of randomized controlled trials requiring long-term follow-up. While patient characteristics influencing adherence are well studied, the influence of contact with clinical staff on this process has received almost no attention. To address this issue the authors evaluated the association of turnover in key clinical research staff with measures of participant adherence to protocol requirements at 40 clinical centers participating in the Women's Health Initiative (WHI), a large multicenter study. Key staff turnover in positions with potential influence on maintaining participant adherence in the Dietary Modification Clinical Trial (DM-CT) and the two Menopausal Hormone Therapy Clinical Trials (HT-CT) of the WHI was determined at each clinical center. Three prospectively established measures of participant adherence for the DM-CT and HT-CT were related to key staff turnover at each clinical center by staff category. More frequent turnover of the clinic practitioner, clinic manager, and principal investigator positions was significantly (p<0.05) associated with lower participant adherence in the HT-CT but was not associated with DM-CT participant adherence. More frequent turnover of the lead nutritionist was not associated with HT-CT participant adherence but was significantly (p<0.05) associated with one measure of decreased DM-CT participant adherence, as would be expected since the lead nutritionist did not typically see the HT-CT participants. These significant and plausible associations suggest that providing consistent contact with key staff in randomized, controlled clinical trials may facilitate long-term participant adherence. Further prospective study exploring process evaluation of the provider side of controlled trial conduct is indicated.

Hormone replacement therapy and menopause: a review of randomized, double-blind, placebo-controlled trials

Hormone replacement therapy (HRT) is frequently prescribed to healthy women to ameliorate menopausal symptoms. HRT is used long term (> or = 1 year) to prevent chronic disease in older women. The objective of this study was to review the benefits and risks of HRT and studies of menopause or HRT in Taiwan via a MEDLINE search. Recommendations are provided for future HRT research in Taiwan. Randomized, double-blind, placebo-controlled clinical trials are considered the gold standard of scientific evidence. A MEDLINE literature search (January 1966-July 2002) identified 23 papers on trials (> or = 1 year) that met the inclusion criteria. The results showed that various HRT regimens used for more than 1 year caused more harm than good in healthy menopausal women and that there was no benefit for women with coronary artery disease, Alzheimer's disease, hysterectomy, hysterosalpingo-oophorectomy, and ischemic stroke. None of this research was conducted in Taiwan. A MEDLINE search using the key words "estrogen replacement therapy and menopause in Taiwan" identified 16 studies. There was only one, short-term, HRT trial. No evidence suggested benefits from long-term HRT in menopausal women in Taiwan.

The randomized world is not without its imperfections: reflections on the Women's Health Initiative Study

In May 2002, the Women's Heath Initiative (WHI) clinical trial, designed to clarify the risks and benefits of combination hormone replacement therapy, came to a premature halt. An interim safety review after an average follow-up of 5.2 years found that a combination of estrogen and progestin often prescribed to postmenopausal women increased the risk of invasive breast cancer, heart disease, stroke, and pulmonary embolism. The combination hormone therapy reduced bone fractures and colorectal cancer, but not enough to outweigh the other risks. The WHI trial presents a challenge for patients, physicians, and epidemiologists, since many observational studies have shown cardiovascular benefits of long-term hormone replacement therapy (HRT). At the same time, a companion paper in the same journal reported an epidemiologic study with a 13.4-year mean follow-up suggesting that estrogen replacement therapy, when used alone for 10 years or more, increases the risk of ovarian cancer. The medical community is still recovering from these twin shocks and trying to digest the results of both of these studies. The WHI study calls into question the long-term use of HRT in healthy women. The benefit of the temporary use of estrogen in controlling disruptive symptoms of the menopause is not being contested. Absent from many news releases are the hedging and equivocation typical of other reported clinical trials. There are still some "hanging chads" out there, and this commentary is designed to examine the uncertainties that remain after the WHI report. It is also intended to suggest development of alternative strategies to control symptoms of the menopausal transition that will reduce risks of HRT. The evidence from the WHI study will need to be incorporated into medical decision making, but clinical decisions, like most human decisions, are complex and in the final analysis must be based on information from many sources.

Multidisciplinary Women's health research: the national centers of excellence in women's health

Contemporary research increasingly needs to consider the value of a multidisciplinary approach in answering critical health questions. The current article outlines the need for multidisciplinary investigations specifically in reference to women's health, and addresses issues related to generating and sustaining interest in such an approach. In addition, the importance of resources and environment for facilitating multidisciplinary research and advocacy efforts for obtaining funding for this approach are discussed. Methodological issues pertinent to the operationalization of multidisciplinary research in women's health are also addressed, and lessons learned from the National Centers of Excellence in initiating multidisciplinary research in women's health are reviewed.

Commentary on the Women's Health Initiative

The Women's Health Initiative (WHI), established by the National Institutes of Health in 1991, is a long-term national health study that focuses on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in postmenopausal women. These chronic diseases are the major causes of death, disability and frailty in older women of all races and socioeconomic backgrounds. The WHI a 15-year multi-million dollar endeavor, and one of the largest U.S. prevention studies of its kind. The study involves over 161,000 women aged 50-79, and is one of the most definitive, far reaching clinical trials of women's health ever undertaken in the U.S. The WHI Clinical Trial and Observational Study will attempt to address many of the inequities in women's health research and provide practical information to women and their physicians about hormone replacement therapy, dietary patterns and calcium/vitamin D supplements, and their effects on the prevention of heart disease, cancer and osteoporosis. Emerging information from the NIH Women's Health Initiative and other studies of women's health begun in the 1990's should be changing the landscape of options for older women in the years to come.

Individually randomized intervention trials for disease prevention and control

It is argued that randomized, controlled trials should fulfil a critical role in the identification of practical approaches to the prevention and control of chronic diseases. Because of the great public health potential of chemopreventive and behavioural approaches to chronic disease prevention there is need for a major interdisciplinary scientific effort aimed at intervention development. Because of the cost and duration of controlled trials to evaluate specific interventions there is a need for well-conducted feasibility, pilot and intermediate outcome trials, to inform and to justify corresponding full-scale trials having clinical disease outcomes. Compared to therapeutic trials, prevention trials need to have a greater emphasis on overall benefit versus risk assessment. Such trials need to be large enough, and of sufficient duration, to yield powerful tests of key hypotheses, and informative benefit versus risk summary statements. These requirements have a range of implications for intervention trial design, conduct, monitoring and reporting, which are reviewed and discussed. The clinical trial component of the ongoing Women's Health Initiative provides illustration throughout this discussion.

Tamoxifen for prevention of breast cancer: report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study

BACKGROUND

The finding of a decrease in contralateral breast cancer incidence following tamoxifen administration for adjuvant therapy led to the concept that the drug might play a role in breast cancer prevention. To test this hypothesis, the National Surgical Adjuvant Breast and Bowel Project initiated the Breast Cancer Prevention Trial (P-1) in 1992.

METHODS

Women (N=13388) at increased risk for breast cancer because they 1) were 60 years of age or older, 2) were 35-59 years of age with a 5-year predicted risk for breast cancer of at least 1.66%, or 3) had a history of lobular carcinoma in situ were randomly assigned to receive placebo (n=6707) or 20 mg/day tamoxifen (n=6681) for 5 years. Gail's algorithm, based on a multivariate logistic regression model using combinations of risk factors, was used to estimate the probability (risk) of occurrence of breast cancer over time.

RESULTS

Tamoxifen reduced the risk of invasive breast cancer by 49% (two-sided P<.00001), with cumulative incidence through 69 months of follow-up of 43.4 versus 22.0 per 1000 women in the placebo and tamoxifen groups, respectively. The decreased risk occurred in women aged 49 years or younger (44%), 50-59 years (51%), and 60 years or older (55%); risk was also reduced in women with a history of lobular carcinoma in situ (56%) or atypical hyperplasia (86%) and in those with any category of predicted 5-year risk. Tamoxifen reduced the risk of noninvasive breast cancer by 50% (two-sided P<.002). Tamoxifen reduced the occurrence of estrogen receptor-positive tumors by 69%, but no difference in the occurrence of estrogen receptor-negative tumors was seen. Tamoxifen administration did not alter the average annual rate of ischemic heart disease; however, a reduction in hip, radius (Colles'), and spine fractures was observed. The rate of endometrial cancer was increased in the tamoxifen group (risk ratio = 2.53; 95% confidence interval = 1.35-4.97); this increased risk occurred predominantly in women aged 50 years or older. All endometrial cancers in the tamoxifen group were stage I (localized disease); no endometrial cancer deaths have occurred in this group. No liver cancers or increase in colon, rectal, ovarian, or other tumors was observed in the tamoxifen group. The rates of stroke, pulmonary embolism, and deep-vein thrombosis were elevated in the tamoxifen group; these events occurred more frequently in women aged 50 years or older.

CONCLUSIONS

Tamoxifen decreases the incidence of invasive and noninvasive breast cancer. Despite side effects resulting from administration of tamoxifen, its use as a breast cancer preventive agent is appropriate in many women at increased risk for the disease.

Design of the Women's Health Initiative clinical trial and observational study. The Women's Health Initiative Study Group

The Women's Health Initiative (WHI) is a large and complex clinical investigation of strategies for the prevention and control of some of the most common causes of morbidity and mortality among postmenopausal women, including cancer, cardiovascular disease, and osteoporotic fractures. The WHI was initiated in 1992, with a planned completion date of 2007. Postmenopausal women ranging in age from 50 to 79 are enrolled at one of 40 WHI clinical centers nationwide into either a clinical trial (CT) that will include about 64,500 women or an observational study (OS) that will include about 100,000 women. The CT is designed to allow randomized controlled evaluation of three distinct interventions: a low-fat eating pattern, hypothesized to prevent breast cancer and colorectal cancer and, secondarily, coronary heart disease; hormone replacement therapy, hypothesized to reduce the risk of coronary heart disease and other cardiovascular diseases and, secondarily, to reduce the risk of hip and other fractures, with increased breast cancer risk as a possible adverse outcome; and calcium and vitamin D supplementation, hypothesized to prevent hip fractures and, secondarily, other fractures and colorectal cancer. Overall benefit-versus-risk assessment is a central focus in each of the three CT components. Women are screened for participation in one or both of the components--dietary modification (DM) or hormone replacement therapy (HRT)--of the CT, which will randomize 48,000 and 27,500 women, respectively. Women who prove to be ineligible for, or who are unwilling to enroll in, these CT components are invited to enroll in the OS. At their 1-year anniversary of randomization, CT women are invited to be further randomized into the calcium and vitamin D (CaD) trial component, which is projected to include 45,000 women. The average follow-up for women in either CT or OS is approximately 9 years. Concerted efforts are made to enroll women of racial and ethnic minority groups, with a target of 20% of overall enrollment in both the CT and OS. This article gives a brief description of the rationale for the interventions being studied in each of the CT components and for the inclusion of the OS component. Some detail is provided on specific study design choices, including eligibility criteria, recruitment strategy, and sample size, with attention to the partial factorial design of the CT. Some aspects of the CT monitoring approach are also outlined. The scientific and logistic complexity of the WHI implies particular leadership and management challenges. The WHI organization and committee structure employed to respond to these challenges is also briefly described.