In a new research letter published in JAMA Pediatrics, a team of Yale experts examined the clinical utility of taking additional measurements in children with high body mass index (BMI) to diagnose pediatric obesity.
Earlier this year, an international expert commission met to determine a new definition of obesity. The commission was seeking a new definition in response to some of the long-discussed limitations of using BMI, which only measures height and weight, as a singular measure to diagnose obesity.
As part of this new definition, the commission recommended that when assessing obesity, in the adult or pediatric population, clinicians should not use BMI alone. They suggested that clinicians use two anthropometric measures—such as BMI and waist circumference or waist-to-weight ratio—or get a direct body fat measurement using, for example, a dual-energy x-ray absorptiometry (DEXA) scan.
Ashwin K. Chetty, BS, lead author of the study, explains, “We wanted to see if taking the recommended additional measurements would add any value, clinically, rather than using BMI alone.”
The researchers found that nearly all U.S. youth aged 8-19 years who had BMI-defined obesity also had commission-defined obesity. Therefore, for youth with BMI-defined obesity, it may not be clinically necessary to use additional body measurements or a costly DEXA scan to diagnose obesity.
The Yale team defined BMI-defined obesity (BDO)—using well-established threshold set by the Centers for Disease Control and Prevention and the American Academy of Pediatrics—for children as “a BMI ≥95th percentile for age and sex” and commission-defined obesity (CDO) as “either two elevated anthropometric measures (BMI, waist-to-height ratio, or waist circumference) or an elevated body fat percentage.”
The group's paper states, “While nearly all youth with BDO had CDO by elevated anthropometric measures and by elevated body fat percentage, nearly all youth who had CDO without BDO had an elevated body fat percentage alone. Among youth with BMI-defined obesity, there may be limited clinical utility in confirming excess adiposity as defined by the expert commission, consistent with prior work in adults.”
Mona Sharifi, MD, MPH, senior author on the report, explains, “Unless there is substantial added value, in a busy primary care practice where many of our patients are seen, it is simply not feasible to slow things down to take additional measurements, especially when some of these measures may be potentially stigmatizing and uncomfortable for children such as taking a waist circumference or involve radiological testing that is costly and comes with low dose radiation exposure. Our results suggest a lack of added value for children with high BMI.”
The research team used data from the National Health and Nutrition Examination Survey (2015-2016 and 2017-2018) and included 3,194 U.S. youth and adolescents aged 8-19 years. DEXA scans are not performed on children aged 8 and under, so all data for children 8 and under were not included.
James T. Nugent MD, MPH, and Ada Fenick, MD, are also co-authors on this research letter.