Published: Apr 8, 2014 | Updated: Apr 9, 2014
By Salynn Boyles, Contributing Writer, MedPage Today

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Action Points

The overall rate of childhood obesity in the U.S. appears to be stabilizing, but the prevalence of extreme obesity among children and teens continues to rise, according to an analysis of national data.

From 1999 to 2012 in the National Health and Nutrition Examination Survey (NHANES) database, severe obesity increased from 3.8% (95% CI 2.7-4.9,P=0.04) to 5.9% (95% CI 4.4-7.4, P=0.04) in the 2- to 19-year-old age group and the prevalence of even more extreme obesity increased from 0.9% (95% CI 0.6-1.3,P=0.002) to 2.1% (95% CI 1.6-2.7, P=0.002), wrote Asheley Cockrell Skinner, PhD, of the University of North Carolina at Chapel Hill in JAMA Pediatrics.

“Nationally representative data do not show any significant changes in obesity prevalence in the most recently available years … unfortunately, there is an upward trend of more severe forms of obesity, and further investigations into the causes of and solutions to this problem are needed,” Skinner and co-author Joseph Skelton, MD, of Wake Forest University in Winston-Salem, N.C., said.

The analysis was one of two studies examining pediatric obesity published this week. A second study in the May Pediatrics suggested that, over the course of a lifetime, higher medical costs associated with childhood obesity average about $19,000 per person, and extra costs average about $12,900 per person when normal-weight children become overweight or obese during adulthood.

“To put these findings in perspective, multiplying the lifetime medical cost estimate of $19,000 times the number of obese 10-year-olds today generates a total direct medical cost of obesity of roughly $14 billion for this age alone,” wrote Eric Andrew Finkelstein, PhD, from the Duke Global Health Institute at Duke University, and colleagues.

Extreme Obesity on the Rise

The study by Skinner and colleagues used the same NHANES data analyzed by CDC researchers who recently reported a decline in obesity rates among preschoolers. Between 2003-2004 and 2011-2012, obesity among 2- to 5-year-olds fell from 13.9% to 8.4%, according to that report.

But Skinner told MedPage Today that the report did not tell the whole story of obesity trends among toddlers in the U.S. because there was an unexpected and unexplained spike in obesity in 2003. Rates have been falling since 2003, but they are not so different from previous years, she said.

“If you go back to 1999, the picture is very different, and you see that rates have been somewhat flat,” she said.

The study was one of the few to examine obesity by category in young children and teens, and the finding that rates of extreme obesity have not fallen and continue to rise is very troubling, Skinner said.

“We may be seeing an overall leveling off of obesity, but among the kids who are at the extremes, it is not what we are seeing,” she said. “And these are the kids who are most at risk for diseases like diabetes. We can’t ignore this and just assume that childhood obesity is getting better.”

A total of 26,690 children, ages 2 to 19, were included in the current analysis. Older children and non-Hispanic black and Hispanic children had higher prevalence rates of overweight and obesity as well as severe and extreme obesity in the group of all years pooled.

In 2011-2012, 32.2% of children in the U.S., ages 2 to 19 were overweight, 17.3% were obese, 5.9% were severely obese, and 2.1% were extremely obese.

“Although these rates were not significantly different from 2009-2010, all classes of obesity have increased over the last 14 years,” the researchers wrote.

The obesity prevalence among 2- to 5-year-olds girls was (P=0.37 for trend):

• 11.1% from 1999-2000
• 10.4% from 2001-2002
• 13.2% from 2003-2004
• 11.5% from 2005-2006
• 10.7% from 2007-2008
• 10.6% from 2009-2010
• 8.0% from 2011-2012 

Boys in that same age range also saw a similar pattern of obesity prevalence at around 10% from 1999-2000, 2001-2002, 2005-2006, and 2007-2008. The prevalence was 14.8% in 2003-2004 and 2005-2006, and 8.8% in 2011-2012 (P=0.93 for trend).

The researchers defined overweight and obesity using CDC criteria, and severe obesity was defined using two additional criteria.

They used a definition of “severe obesity” recommended by the American Heart Association as a body mass index (BMI) greater than 120% of the 95th percentile for age and sex or a BMI of 35 kg/m² or greater, whichever was lower. This was used in place of the 99th percentile because it has been shown to demonstrate more stability in estimation. It was used to represent class 2 obesity in adults and was used in this study to define severe or class 2 obesity in children and teens.

Their definition of a more extreme obesity, considered class 3 obesity in adults, was a BMI greater than 140% of the 95th percentile for age and sex or a BMI greater than or equal to 40 kg/m².

The prevalence of class 2 and class 3 obesity increased for children and teens overall:

• 1999-2000: 3.8% (95% CI 2.7-4.9) and 0.9% (95% CI 0.6-1.3)
• 2001-2002: 5.1% (95% CI 4.1-6.1) and 1.3% (95% CI 0.9-1.7)
• 2003-2004: 5.1% (95% CI 3.8-6.4) and 1.6% (95% CI 0.9-2.2)
• 2005-2006: 4.8% (95% CI 3.5-6.1, P=0.04) and 1.2% (95% CI 0.6-1.8, P=0.002)
• 2007-2008: 5.0% (95% CI 3.8-6.2) and 1.5% (95% CI 1.0-2.0)
• 2009-2010: 5.7% (95% CI 4.5-7.0) and 1.6% (95% CI 1.1-2.1)
• 2011-2012: 5.9% (95% CI 4.4-7.4) and 2.1% (95% CI 1.6-2.7) 

The study had some limitations. The authors were unable to examine state-specific obesity trends and they lacked a sufficiently large sample to examine very specific trends among children and teens in the class 3 obesity category. Still, they concluded that the analysis raised new concerns about the upward trend of more severe forms of obesity among children and teens.

“The interventions we are using are really not having the effects we had hoped in this group of children,” Skinner said.

The Cost of Obesity

Finkelstein and colleagues identified the best, current estimate of the incremental lifetime per capita medical cost of an obese child in the U.S. today relative to a normal-weight child.

“An estimate of the lifetime medical costs of an obese child provides a benchmark of the potential per capita savings that could accrue from successful childhood obesity prevention efforts,” they wrote.

The review included studies published over the last 15 years, identified through PubMed and Web of Science searches. Two reviewers independently screened search results and extracted data from eligible articles. All estimates were inflated to 2012 dollars and discounted to reflect today’s costs for a 10-year-old child.

Six studies were identified. The incremental lifetime direct medical cost from the perspective of a 10-year-old obese child relative to a 10-year-old normal-weight child ranged from $12,660 to $19,630 when weight gain through adulthood among normal weight children was accounted for, and from $16,310 to $39,080 when this adjustment was not made.

The researchers settled on an estimate of $19,000 as the incremental lifetime medical cost of an obese child relative to a normal-weight child who maintained normal weight throughout adulthood. They noted that the study with the highest estimate ($39,080) did not adjust estimates, as several other studies had, to offset inflated costs at lower ages.

They pointed out that even if the most conservative adjusted estimate of $12,660 was used, the total direct medical cost for the same cohort of 10-year-olds would still be $9.4 billion which is 62 times the 2012-2013 funding for the nationwide “Fresh Fruit and Vegetable Program” designed to increase the consumption of among school-age children.

They also calculated that “on a per capita basis, the cost of one year of college (including tuition, fees, books, room and board, and other expenses) at a public, 4-year institution is roughly $16,930. Thus, each case of childhood obesity that could be prevented and maintained (at no cost) would allow for funding ≥1 year of a child’s college education.”

The group cautioned that medical cost-estimates do not account for obesity’s effect on health-related quality of life or on nonmedical costs, such as decreased productivity.

“There is the potential to improve weight management among all youth that could last well into adulthood,” they concluded.

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