Junkfood Science: Experimenting on a new generation

January 17, 2007

Experimenting on a new generation

When the U.S. Preventive Services Task Force released its latest ruling, Screening and Interventions for Childhood Obesity, and a summary of the evidence, its six-member Childhood Obesity Working Group also published a weighty commentary concerning that evidence in the journal Pediatrics. What was remarkable about the Working Group’s statement was its outright condemnation of clinicians and professional organizations that support BMI screening of children and its palpable incense over the lack of quality evidence to support childhood obesity interventions.

It’s unclear if this later upset was because there wasn’t enough evidence for them to credibly support the obesity initiatives of the U.S. Department of Health and Human Services or their own beliefs about overweight in children as harmful for which something must be done about it. Nonetheless, the forcefulness of their statements are remarkable given how significantly they dispute the policies of their sponsor, the HHS’ Agency for Healthcare Research and Quality. It charges them to issue evidence-based findings that the HHS uses to justify its policies and spending. But its 2006 Congressional budget report noted, that they have been making “significant improvements in realigning the work we do with our strategic goals and those of the Department [of HHS].”

In their commentary, “Screening for Overweight in Children and Adolescents: Where Is the Evidence?,” the Working Group began with an unprecedented chastising of the American Academy of Pediatrics and American Academy of Family Physicians for their endorsements of universal screening of children using body mass index (BMI) and for their use of BMI growth curves to identify obese and overweight children. This side of the story, while it was the bulk of their article, didn’t make the news, so let’s see what they wrote.

The USPSTF group took issue with these physician groups for supporting such practices and pointedly said that it didn’t matter how popular the practice might be among experts or how many endorsed it. Instead, it said the USPSTF “adheres strongly to a policy of making recommendations only in the presence of sufficient evidence of adequate quality...even for a practice that may be supported by expert consensus or less rigorous evidence.”

In other words, consensus of opinion does not make for scientific support, only credible evidence can do that. The Working Group described its analysis of the evidence:

Because most preventive interventions have not been tested in rigorous randomized trials, the USPSTF uses an analytic framework to describe the causal pathway between the preventive intervention and important health outcomes. If direct evidence linking the preventive intervention to a health outcome is unavailable, the USPSTF seeks high-quality evidence for each of the linkages in the analytic framework. No randomized trials of screening for childhood overweight or obesity in the clinical setting were found in the comprehensive literature review...Unfortunately, very little high-quality evidence was found to address any of the key questions.

They reviewed programs with published results. While perhaps extensive in number, those are still a small segment of the massive public and private efforts to address childhood obesity that are active in communities and schools across the country, through governmental agencies, faith-based groups, schools, professional societies, health organizations, advocacy groups, philanthropies, workplaces and political organizations. To assess and coordinate these efforts, centralize information, and develop clinical guidelines and a national action plan, a private-government coalition was formed in 2003 called Shaping America's Youth (SAY).

SAY is funded by corporate sponsors; administered through a PR and telecommunications firm, Academic Network, LLC; and is partnered with the American Obesity Association, the Office of the Surgeon General, HHS, American Academy of Pediatrics, American Diabetes Association, American College of Sports Medicine, University of California Davis, and the North American Association for the Study of Obesity. SAY released its comprehensive analysis, “National Survey and Registry of Programs Addressing Childhood Physical Inactivity and Excess Weight,” in August 2005 and it provides important insights into these programs.

SAY found that more than $800 million was funding these initiatives, most of which focused on increasing physical activity and improving diets, directed at 4.6 million children each year. Eight out of ten programs specifically targeted kids over 6 years of age and 20% were aimed at infants, toddlers and pre-schoolers. Fat children were targeted in 2/3 of the programs and the largest segment of participants were low-income. While the programs appear altruistic, two-thirds admitted their programs were created to support their marketing and corporate branding, and 100% were developing products and services using the child obesity issue. The largest motivating factor (admitted by 20% of the organizations) for initiating their programs was “increasing public perception of a health care crisis.”

While most organizations claimed to have outcome measures and published data on their program’s effectiveness, SAY found than less than 5% actually had published their data in a professional journal and half of the programs didn’t even have quantifiable outcome measures. Despite these weaknesses, the SAY registry was used by the Institute of Medicine in the development of its report, “Progress in Preventing Childhood Obesity: How Do We Measure Up?,” according to David McCarron, M.D., SAY executive director.

The commentary by the Working Group used strong language when describing the pervasive problem of not understanding the potential harms of childhood obesity initiatives, admonishing: The first principle of medicine is well known: primum non nocere (first, do no harm).”

[W]e have little information about the potential harms of screening, such as labeling, reduced self-esteem, poor eating habits, eating disorders, adverse family relations, or the effects of continuing to lose and regain weight (yo-yo dieting).... If we forge ahead with an intervention (whether therapeutic, preventive or even diagnostic) without knowing whether it is beneficial, we run the risk of causing unintentional harm.

First of all, screening and measuring children’s BMIs simply doesn’t address the real issue of health. BMI in early childhood, they stated, poorly predicts BMI in adulthood for any given child.

Other risk factors such as genetics, fitness, ethnicity, and gender may also significantly affect health outcomes, so that the long-term health risks may be higher for some "normal"-weight children than it is for children who are overweight as measured by BMI alone. Screening using a BMI or BMI percentile cutoff will miss these children.

We don’t know whether screening for obesity and overweight does any good. We don’t know how strong the linkages in the analytic framework are. For example, we don’t know whether screening correctly identifies children at risk for future adverse health outcomes; which treatment best helps those who have been identified (even if they have been identified correctly); and whether intermediate outcomes such as weight loss or stabilization lead to long-term health. The USPSTF found that the evidence it would need to make such a recommendation is not there.

In closing, they gave a brief mention of the Institute of Medicine’s action plan with goals for preventing obesity in children and youth, “implementing population and individual strategies based on the best available evidence to address policy, environmental, and behavioral factors associated with obesity.” What they left out was that this Robert Wood Johnson Foundation-commissioned and funded IOM report, “Preventing Childhood Obesity: Health in the Balance,” also noted the lack of evidence for its far-reaching recommendations:

Presently, there is limited experimental evidence regarding the best ways to prevent childhood obesity and the extent to which various potential factors contribute to weight gain.

Nevertheless, RWJF President and CEO Risa Lavizzo-Mourey, M.D., said in a press release: “There are ‘natural experiments’ taking place...but we can’t afford to surrender an entire generation of kids to the obesity epidemic while we wait for perfect answers.”

How much has the perception of an obesity crisis been created, a case of marketing and “seek and ye shall find;” and how much is real? [More on that later.]

Undeniably, the all-out, widespread efforts to address childhood obesity are disproportional to the evidence and have a disturbing level of vested interests behind them. Yet, few parents are aware just how little evidence there is for the screening, preventive measures designed to modify activity and diets, or therapeutic interventions their children are being subjected to. And it is unimaginable that many parents are keen on the idea of experimenting on their growing children with nothing credible to go on.

© 2007 Sandy Szwarc

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