Elected officials, public health officials, rating agencies, and many others rely heavily on self-reported data to support understanding, create policy, and spur action. The state of Tennessee annually measures height and weight in school-aged children to conduct objective surveillance of weight status among this population. In these analyses, we have seen a small, but statistically significant, decrease in obesity and overweight trends over the past 5 years.

Recently, results from survey data were reported nationally, prompting the Tennessee Department of Health, in partnership with Department of Education's Office of Coordinated School Health (CSH), to review directly measured anthropometric data compared with self-reported survey data for the children in our state. We found a substantial and significant difference between self-reported data and the CSH data, especially in the obesity rates for high school-aged children. The Youth Risk Behavior Survey (YRBS) 2013 reported the obesity rate for high schoolers to be 16.9% compared with the CSH data reporting 25.2%.1 Data from the National Survey of Children's Health (NSCH) reported the 2011 obesity rate among 10- to 17-year-olds in Tennessee as 20.5%, whereas the CSH data showed the rate to be 24.2% among children of a similar age range.2 YRBS data were collected in schools, as were CSH data, but do not cover each school district in the state. NSCH was administered via telephone to approximately 2000 Tennessee children, whereas CSH data collected measurements from approximately 20 000 children in the NSCH age range.

Beyond each survey's methodology and the weighted nature of survey data, the differences may be rooted in biases related to response. As a brief review of the literature on this topic confirmed, a tendency exists in both adults and children to underestimate weight and overestimate height, which will certainly bias body mass index calculations toward being lower than the actual values. Although this bias is described elsewhere, policy makers may discount this information in ways that can impact policy and public health action. Most importantly, uninformed examination of survey data may lead us to believe things are better than they actually are.

We are shedding light on this issue because we believe our statewide data are relatively unique in their ability to provide measured height and weight data from our school-aged population. While biases do exist even in objective measurement, these biases are likely to pale in comparison with those of self-reported data. Given the magnitude of the obesity epidemic and the stigma associated with what well over half of our population struggles with, consideration should be given to these types of direct collections for the purposes of scientific and clinical action as well as toward efforts to destigmatize this ongoing epidemic.

-Kimberly R. Glenn, PhD, MPH

Office of Healthcare Statistics

Division of Policy

Planning and Assessment

Tennessee Department of Health

Nashville

([email protected])

- Lori Paisley, BS

Coordinated School Health

Tennessee Department of Education

Nashville

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