Water Trio

Does Childhood Obesity Cause Puffery?

Cascades of headlines this week claim that water fountains offer a simple solution to childhood obesity. These excessive claims are part of a larger pattern that has us wondering. What is it about childhood obesity that leads otherwise sensible people to spout puffery?

The paper that’s causing this week’s nonsense was published in JAMA Pediatrics, and the authors bear some responsibility for starting a frenzy of misleading headlines. What they did was conduct an uncontrolled, observational study of the installation of “water jet” units to dispense drinking water in New York City schools. They describe it as “quasi-experimental.” That means it has some superficial characteristics of an experiment, but it’s just an observational study.

This limitation doesn’t stop them from making claims of cause and effect that would only be justified by a real experiment. It’s right there in the title: “Effect of a school-based water intervention on child body mass index and obesity.” The fact is, they only measured associations, not effects. Apparently the distinction between correlation and causation is also lost on the editors who invited an editorial on the study. The editorial gushes, saying: “Sometimes, a very simple intervention can have a powerful effect.” Spurred by such academic puffery, health reporters have had a field day. Live Science tells us: “Water jets may stem the tide of childhood obesity.”

To its credit, HealthDay summed things up more accurately than the JAMA Pediatrics. “Schools offering drinking water may have slightly slimmer students” was their headline. Not exactly “a powerful effect.”

In fact, the effect might be just the reverse. Schools that were first in line to get these magic water jets might have other factors at work that are responsible for them having a little bit less obesity. This is why a valid controlled study is so important.

In discussing their findings, the authors make reference to a 2009 study in Germany and characterize it as “a randomized clinical trial.” They were trying to suggest that their own study adds to a solid base of evidence. But in fact, the study they referenced was a cluster-randomized trial with design flaws that “made causal statistical inferences impossible and the study invalid” according to a 2015 publication in the American Journal of Clinical Nutrition.

The investigators behind this week’s headlines and the journal that promoted their study are fueling a problem that undermines scientific integrity. In a 2010 analysis, scientists in epidemiology, public health, biostatistics, and obesity research from the University of Alabama at Birmingham explained:

The quality of reporting of observational studies is an important issue. We found inappropriate use of causal language in the abstracts or titles of almost one third of human observational obesity or nutrition related study reports in four major obesity and nutrition journals. This is troubling because it misleads readers, particularly those who only peruse titles and abstracts. This may be especially true for less scientifically trained readers including reporters in the mass media who often have little scientific training and often describe themselves as having difficulty with key tasks involved in scientific reporting.

It is little wonder that the public is skeptical about nutrition and health guidance. Researchers and journals need to clean up their act. Puffery has no place in the publication of health research.

“The fault, dear Brutus, is not in our stars, but in ourselves.” — William Shakespeare

Click here to read the study, here to read the editorial, and here to read more from HealthDay. For more perspective on accurate reporting of observational studies, click here.

Water Trio, photograph © Lois Elling / flickr

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January 22, 2016

8 Responses to “Does Childhood Obesity Cause Puffery?”

  1. January 22, 2016 at 6:04 am, Joe Gitchell said:

    Yet another similarity with the world of nicotine, Ted.

    Give me strength!

    Joe

  2. January 22, 2016 at 6:46 am, Allen Browne said:

    Yup – or as Scotty said “Beam me up, there is no intelligent life down here.”

    But I did have to look up ‘PUFFERY”. I would have guessed it was high in added sugar.

  3. January 22, 2016 at 7:25 am, Ted said:

    Thanks, Allen! Puffery is a standard tool of advertising. “We have the best coffee in the world!” Puffery requires no substantiation, because people are supposed to disregard it.

  4. January 22, 2016 at 7:27 am, Ted said:

    Gathering real evidence seems so tedious when someone know they’re right. I feel your pain, Joe.

  5. January 22, 2016 at 1:10 pm, Angela Meadows said:

    Yes! So much this.

  6. January 22, 2016 at 1:25 pm, Ted said:

    Thanks, Angela. I, too have had enough of this sort of puffery.

  7. January 22, 2016 at 2:06 pm, Sam Jones said:

    Ted, I thought it was possible to results as a causal effect when using a difference-in-difference design, which is what the study does?

  8. January 22, 2016 at 6:40 pm, Ted said:

    Such statistical methods can help form suppositions about causality, but when you have a small effect and no randomization, proof of causality remains out of reach. Certainly, characterizing this as a “powerful effect” is absurd.