Lawrence Wein: Childhood Obesity Screening May Not Be That Useful
A new study explains why.
A little boy jumps through a fountain on a hot summer day. (Reuters photo by Brian Snyder )
It makes intuitive sense: If you want to want to tackle the epidemic of obesity among adults, try stopping it in childhood.
Around the country, hospitals and other health care providers have set up intensive six-month programs to treat obese children as young as 6. Children and their parents get dietary training, exercise regimens, and weekly family counseling about healthier lifestyles. The idea is that children will not just slim down but also develop healthier habits that will stay with them well into adulthood. The U.S. Preventive Services Task Force, a panel of independent health care experts convened by the government, recommends such treatment for all obese children 6 years or older.
But a new Stanford study — drawing on health data going back 40 years, as well as some more limited data on the results of treating obesity in children — suggests that this head-on treatment of youngsters will have a surprisingly meager impact on reducing obesity-related illness in adulthood.
The problem, in a nutshell, is that people go through a great many changes as they grow up. Many obese children slim down without any special treatment, and many thin children become overweight as adults. Even if children get treatment at the age of 6 or 8 that’s considered successful, the researchers say, many will be obese again by the time they are 30 or 40. And many who weren’t obese at young ages will be obese later.
The new study, “Analyzing Screening Policies for Childhood Obesity,” appeared in the April 2013 issue of Management Science. It was conducted by Lawrence M. Wein, a professor at Stanford’s Graduate School of Business; Yan Yang, a recent graduate of the doctoral program at Stanford’s Institute for Computational and Mathematical Engineering; and Jeremy D. Goldhaber-Fiebert, assistant professor at Stanford’s School of Medicine.
Some of their findings:
- Intensive obesity treatment has very little impact on the likelihood that obese 6-year-olds will suffer from hypertension as adults. A full 25.1% of those who receive treatment will have hypertension by the time they are 40, for example, compared to 26.8% of those who don’t get treatment.
- Early childhood screening for obesity has limited predictive value for health in adulthood. The researchers calculate that 18.8% of 6-year-olds who are not obese will suffer from hypertension by the time they reach 40.
- You would have to provide intensive treatment to 20 obese 6-year-olds to get just one less case of adult hypertension when those individuals are 40.
- Intensive treatment has a more significant long-term impact for 16-year-olds, but even that effect may be modest. The researchers predict that about 34.9% of obese 16-year-olds who get treatment would still develop obesity-related illnesses by the age of 40, compared to 39.4% of those who didn’t get treated at age 16.
No one disputes that obesity is an epidemic health problem in the United States. About 35% of American adults are obese, a two-fold increase since 1980. Roughly 17% of children are obese, about triple the rate in 1980. Estimates of the cost of treating Americans of all ages for obesity-related illnesses, such as diabetes and cardiovascular disease, range as high as $190 billion per year.
While educating children and families about exercise and diet might be useful to individual youngsters, the issue under study at Stanford was whether widespread, intensive treatment for obese young children offers much bang for the buck. A six-month program can easily cost $3,500 per child, so treating every obese child in the United States would cost billions, and the number of service providers needed would probably far outstrip the number who currently offer treatment. At the moment, relatively few obese children get such treatment, because both public and private insurance programs are reluctant to cover it.
For any given amount of money spent on treatment, the Stanford researchers estimate, concentrating on teenagers who are 16 or older would produce a slight increase in health benefits compared to treating all obese children from the ages of 6 to 18. Alternatively, the cost of obtaining the same long-term reductions in adult obesity-related illness could be reduced by 28% by focusing on 16-year-olds.
An even smarter strategy from a public policy standpoint, the researchers argue, could be to put more money into universal efforts aimed at all children ― better nutrition in the schools, better playgrounds and fitness programs in the schools, and public efforts to reduce consumption of junk food ― rather than focusing on just obese children.
“There are a lot of good things we can do in the schools, in the supermarkets of big cities, in the food industry, and in the beverage industry,” says Wein. “From a cost-effectiveness standpoint, I believe this would be a better way.”
The new study is likely to be controversial. Because almost no children received intensive obesity treatments back in the 1970s or 1980s, the researchers used statistical modeling to infer the long-term benefits. It sounds highly theoretical, but the approach is analogous to predicting the trajectory of a hurricane and then estimating how much a change in conditions would knock the hurricane off the path originally predicted.
The researchers began by getting a baseline for what happens to children in the absence of treatment, drawing on two national data sets that tracked the health conditions of children and adults over several decades. That allowed them to estimate the likelihood that children of particular weights and ages will suffer from diabetes or hypertension by the time they are 40. The researchers then combined those long-term probabilities with shorter-term results from studies of children who did and who did not receive treatment.
Businesses have used similar types of statistical modeling for years to make decisions about the timing of production, inventory acquisition, shipping, and many other issues. Wein, who began his career by using mathematical tools to optimize manufacturing systems, has used them for more than two decades to analyze potential social and health challenges: responding to disease pandemics, optimizing emergency nutrition during famines, dealing with bioterrorist threats.
The researchers emphasize that there may still be important short-term reasons to intensively treat obesity in some younger children. They also caution that their study doesn’t imply that parents should stop worrying if their children are seriously overweight. But if a prime goal of intensive childhood treatment is to reduce chronic disease in adults, they say, there are better ways to tackle the problem.
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