I have yet to understand why some scientific reports make a big splash in the popular press while others, however worthy, do not. For example, I am still scratching my head over a New England Journal of Medicine report officially published today (I received the journal several days ago) entitled, “Incidence of childhood obesity in the United States,” and written by SA Cunningham and colleagues from Emory University in Atlanta. The scientific study results made the front page of today’s NYT in an article entitled, “Obesity is found to gain its hold in earliest years, ” and was written by Gina Kolata. If you want the read about the study, I think the NYT article ( January 30, 2014, page A1) is a fine place to start, and perhaps, less confusing to interpret than the scientific article, which was accompanied by an editorial entitled, “Who becomes obese during childhood-clues to prevention,” and written by SL Gortmaker and EM Taveras.
What was the study all about?
Cunningham et. al., evaluated data from a longitudinal study called the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999. The study was designed and conducted by the National Center for Education Statistics (NCES) of the United States Department of Education. The study enrolled 21,260 children who were starting kindergarten. The NCES investigators followed 9358 of these children through 8th grade. Cunningham et. al., analyzed data from a subset of these children (n = 7738) for whom data collection was complete. Trust me, the scientific paper is not easy to follow unless one has a Ph.D. in statistics, but the take-home message is a simple one: children who are overweight (defined as BMI 85th-94th percentile) at age 5 years, are 4 times more likely to be obese (defined as BMI 95th percentile or greater) at age 14 years than children who were not overweight at age 5 years. In addition, the higher the birth weight, the more likely the child was to be overweight at age 5 years (the study did not have any weight data on the children after birth until age 5 years). One very interesting finding that was presented in the “results” section of the paper, but not discussed in either the scientific paper or the NYT article, was that children from the wealthiest 20% of families had a much lower prevalence of obesity at age 5 years than did children from all the lower socioeconomic quintiles, and that was also true at all ages and the differences increased steadily with age.
Based on their data, Cunningham et. al., speculate that obesity-prevention programs that focus on children who are overweight by the age of 5 years “may be a way to target the children who are most susceptible to becoming obese during later childhood and adolescence.” I couldn’t actually figure out what Gortmaker and Tavaras meant when in their editorial on the paper by Cunningham et.al., they wrote the following regarding treatment strategies: “Clinical interventions are just one approach, since evidence increasingly suggests that multilevel, multisector approaches that focus on children’s environments and that aim to alter early life systems are likely to be most effective in preventing obesity in populations.” Sounds interesting, I guess?
What is my take on all of this?
I applaud Cunningham and colleagues for their hard work in putting study data together, but frankly, there is nothing new here. We already knew that childhood obesity is a serious problem and that the antecedents for obesity in later childhood and in adulthood start early-on (at birth as the Cunningham et. al. data suggest). We just don’t seem to know what to do about the problem. One thing we can do is try to figure out what the socioeconomic data mean; is it genetics, education, access to healthier foods, more recreational opportunities, or what? Finally, I am not critical of Gina Kolata for writing about this study, but I wonder who at the NEJ felt this study was so compelling to publish and even to have an accompanying editorial given the many earlier studies that had addressed the same basic questions that Cunningham et.al. did, and with more-or-less identical conclusions.