U.S. Employs Flawed Scientific Method in Attempt to Quell W.H.O. Report
American Institute for Cancer Research
AICR Letter Criticizes Bush Administration's Outmoded Criteria for Judging Science on Disease Prevention
The American Institute for Cancer Research (AICR) today sent a strongly worded letter to Tommy G. Thompson, Secretary of the Department of Health and Human Services. In the letter, AICR charged that the criteria used by US health policy makers to craft advice for disease prevention isn't keeping pace with the changing scientific landscape.
AICR Executive Vice President Kelly Browning called on the Bush Administration to acknowledge the many differences that exist between disease treatment and disease prevention. Until US health policy makers rethink their reductionist assumption that a single method can be used to investigate these different scientific fields, the AICR letter said, federal prevention policy will remain "fundamentally flawed."
"The way to assess the potential of a drug to cure an illness is not the way to assess the potential of overall diets to prevent the illness in the first place," said Browning. "Yet it is still official US health policy to attempt to answer these very different questions with a single set of scientific criteria. This practice is unfortunate and ultimately misleading. When it comes to the multifaceted issue of prevention, one size does not fit all."
According to the AICR letter, many in the international scientific community who study prevention shun the Federal Government's reductionist focus on randomized controlled trials (RCTs) and have instead embraced the more comprehensive "portfolio approach" to study the issue.
The portfolio approach assesses the many different forms of scientific evidence together, without giving any single form greater weight. According to the AICR experts, this comprehensive method can answer complex, interrelated questions about the prevention of chronic disease that RCT-focused efforts – which study disease treatment – are simply not designed to ask.
Bush Admin Clashes with W.H.O.
The sharp distinction between these two approaches came to a head as recently as last month, when the Bush Administration sent its own letter to the World Health Organization (WHO) and the Food and Agriculture Organization (FAO). In the letter, William R. Steiger, Special Assistant to the Secretary for International Affairs at the US Departments of Health and Human Services (HHS) and Agriculture, criticized the methodology behind a draft of the WHO/FAO Report, "Diet, Nutrition and the Prevention of Chronic Diseases."
The HHS criticism centered on the fact that the WHO/FAO draft did not use the same set of "Evidence-Based Guidelines" used by all federal health agencies. These guidelines involve a hierarchy of evidence in which the results of randomized controlled trials supersede results from other kinds of scientific investigation.
RCTs Ask the Wrong Questions, Scientists Say
But researchers at WHO and other international organizations have been saying for years that using a single "hierarchy of evidence" to answer the vastly different questions of treatment and prevention is shortsighted and misleading.
The prevention experts at AICR maintain that RCTs – which measure the effects of a specific treatment in patients with an already existing disease – cannot and do not speak to the more multifaceted question of disease prevention.
Although the randomized controlled trial is still considered the scientific "gold standard" in the US, to growing numbers of prevention researchers in the international scientific community, RCTs are only one investigative tool among many.
"A clinical trial that investigates the diet-cancer connection, for example, can only ask: will this specific dose of this isolated food substance given to this group of cancer patients keep their cancers from returning over this particular short period of time?" according to the AICR letter.
AICR experts believe that this is an important and potentially life-saving question to answer, Browning said. But they insist that a much larger question must also be asked: What sort of everyday diet and exercise over a person's lifetime can help lower the chances of getting cancer in the first place?
Portfolio Approach Offers Perspective Shaped By "Real World" Results
The portfolio approach considers results from randomized clinical trials alongside other evidence such as laboratory studies, metabolic studies, case-control studies, cohort studies and studies that examine the diets and disease rates of entire populations. By examining the possible links between diet and disease from all of these perspectives simultaneously, a portfolio approach can reflect the kind of pre-existing "real world" situations that occur outside of a clinic.
This change in scientific thinking is sweeping. Even the most vocal proponents of using hierarchies of evidence for clinical treatments have come to recognize that method's deficiencies. Three prominent researchers wrote in the January 3rd, 2004 edition of the British Medical Journal decrying "inflexible use of evidence hierarchies."
In the paper, Paul Glasziou of the University of Oxford, Jan Vandenbrouck of Leiden University in the Netherlands, and Ian Chalmers of the James Lind Initiative in Oxford, England complain that "criteria used to guide inferences about the main effects of treatment have been uncritically applied" to questions about other aspects of health, including chronic disease prevention.
Motivation for US Objections Questioned
While experts at AICR are urging the Bush Administration to accept a more comprehensive approach to prevention, some public health advocacy groups have charged that the Administration's chief objections to the WHO/FAO draft are not rooted in an objective appraisal of the global science at all. These experts note that much of the Bush Administration's criticisms center on the controversial issue of obesity prevention.
Specifically, the Administration found fault with WHO/FAO's proposed guidelines for combating obesity on a global scale, including efforts to limit the marketing of food and soft drinks to children. Some advocates detect in this resistance the backdoor influence of such industry interests as fast food marketers and the sugar lobby.
Whatever the political reasons for the Bush Administration's objections, the AICR letter focuses on the science behind those objections, which it calls "ill suited to issues of prevention." The letter concludes, "We therefore urge you now to rethink the fundamental misconceptions that currently lie at the heart of US policy on disease prevention."
For more information, or to contact American Institute for Cancer Research, see their website at: www.aicr.org
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