Last week, I read this article in the Jan 14, 2010 NY Times: Obesity Rates Hit Plateau in U.S., Data Suggest (http://www.nytimes.com/2010/01/14/health/14obese.html) I found this hard to believe, but hey, it supposedly came straight from the CDC - hard to argue with.
We examined this further in my class tonight. I must give credit to Joyce Vergili, EdD, RD, CDE for doing the breakdown for us in class. Some of the highlights are below. I was a bit surprised at this: The NY Times usually does an OK job, but they really did misinterpret this study, which only serves to propagate confusion.
The NY Times states that, "Americans, at least as a group, may have reached their peak of obesity, according to data the Centers for Disease Control and Prevention released Wednesday." This sounds like big news! Yet, go to the CDC website, and there is nary a mention of this mysterious data. Turns out, the numbers were actually published in the Journal of the American Medical Association (JAMA) using data from the ongoing NHANES (National Health and Nutrition Examination Surveys). It was not "just released" data. It was NHANES data from 1999 - 2008. NHANES data is actually available to the public, if you care to learn how to manipulate the database.
Here is the link to the entire JAMA article, published online: http://jama.ama-assn.org/cgi/content/full/303/3/235
Anyway, where the NY Times really screws up is the following: "The numbers indicate that obesity rates have remained constant for at least five years among men and for closer to 10 years among women and children — long enough for experts to say the percentage of very overweight people has leveled off."
What the authors, Flegal et al., actually state regarding this is: "In 2007-2008, the prevalence of obesity was 32.2% among adult men and 35.5% among adult women. The increases in the prevalence of obesity previously observed do not appear to be continuing at the same rate over the past 10 years, particularly for women and possibly for men."
Let's be clear here. Did the authors say we have plateaued? No! They simply state the prevalence has changed. Has it slowed? Maybe. Seems likely. But stopped? No. Take a look back at the first sentence of the NY Times piece, when it states Americans "may have reached their peak of obesity." One classmate pointed out this sentence makes it sound as if rates are declining. I'm not exactly sure how Dr. Deitz (interviewed for the Times piece) can say we've "halted the progress of the obesity epidemic" based on these data. At the very best, it appear it might be slowing - very different than halting altogether.
The NY Times also fails to point out the weaknesses of the study, as noted by the authors (possible sampling error, reliance on BMI and that they limited statistical power: "The power of this study is limited to detect small changes in prevalence, particularly among subgroups defined by sex, age, and racial and ethnic group."
How many people reading the NY Times piece think we have now stopped obesity in its tracks?
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