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Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Severe obesity and cardiometabolic risk in children: comparison from two international classification systems
Giuliana Valerio1, Claudio Maffeis2, Antonio Balsamo3
1Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Napoli, Italy.
Insights
Defining severe obesity (Sev-OB) in children requires careful consideration of reference standards. The 1.2 times the 95th percentile of body mass index (BMI) better identifies children with cardiometabolic risks than the 99th percentile.
Area of Science:
- Pediatric Endocrinology
- Public Health Nutrition
- Cardiology
Background:
- A universally accepted definition for severe obesity (Sev-OB) in children is lacking.
- Body mass index (BMI) percentile curves from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) are commonly used to define obesity in children.
- Different cut-points within these curves may lead to varied estimates of Sev-OB and associated health risks.
Purpose of the Study:
- To compare estimates of severe obesity (Sev-OB) in children using different body mass index (BMI) percentile cut-points from CDC and WHO growth charts.
- To evaluate the effectiveness of these different cut-points in screening for cardiometabolic risk factors in overweight and obese children.
Main Methods:
- A cross-sectional, multicenter study included 3,340 overweight/obese children.
- Severe obesity (Sev-OB) was defined using two criteria: BMI ≥ 99th percentile or BMI ≥ 1.2 times the 95th percentile, based on both CDC and WHO growth curves.
- Cardiometabolic risk factors included high blood pressure, hypertriglyceridemia, low High-Density Lipoprotein cholesterol, and impaired fasting glucose.
Main Results:
- Prevalence estimates of Sev-OB differed significantly between CDC and WHO references, with WHO identifying a higher proportion of children as severely obese.
- The 99th percentile cut-point showed lower sensitivity but higher specificity and positive predictive value compared to the 1.2 times the 95th percentile for identifying children with ≥ 2 cardiometabolic risk factors.
- Using the 1.2 times the 95th percentile demonstrated substantial agreement between growth curves, particularly in children aged 10 years and younger.
Conclusions:
- The choice of reference system (CDC vs. WHO) and BMI cut-point significantly impacts the definition of severe obesity and the identification of cardiometabolic risk in children.
- The 1.2 times the 95th percentile of BMI, from either CDC or WHO standards, offers a better discriminatory ability for identifying severely obese children with increased cardiometabolic risk compared to the 99th percentile, especially in younger children (≤10 years).
Objectives:
There is no agreed-upon definition for severe obesity (Sev-OB) in children. We compared estimates of Sev-OB as defined by different cut-points of body mass index (BMI) from the Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO) curves and the ability of each set of cut-points to screen for the presence of cardiometabolic risk factors.
Research Design And Methods:
Cross-sectional, multicenter study involving 3,340 overweight/obese young subjects. Sev-OB was defined as BMI ≥ 99(th) percentile or ≥ 1.2 times the 95(th) percentile of the CDC or the WHO curves. High blood pressure, hypertriglyceridemia, low High Density Lipoprotein -cholesterol and impaired fasting glucose were considered as cardiometabolic risk factors.
Results:
The estimated prevalence of Sev-OB varied widely between the two reference systems. Either using the cut-point ≥ 99(th) percentile or ≥ 1.2 times the 95(th) percentile, less children were defined as Sev-OB by CDC than WHO (46.8 vs. 89.5%, and 63.3 vs. 80.4%, respectively p<0.001). The CDC 99(th) percentile had lower sensitivity (58.5 vs 94.2), higher specificity (57.6 vs 12.3) and higher positive predictive value (34.4 vs 28.9) than WHO in identifying obese children with ≥ 2 cardiometabolic risk factors. These differences were mitigated using the 1.2 times the 95(th) percentile (sensitivity 73.9 vs. 88.1; specificity 40.7 vs. 22.5; positive predictive value 32.1 vs. 30.1). Substantial agreement between growth curves was found using the 1.2 times the 95(th) percentile, in particular in children ≤ 10 years.
Conclusions:
Estimates of Sev-OB and cardiometabolic risk as defined by different cut-points of BMI are influenced from the reference systems used. The 1.2 times the 95(th) percentile of BMI of either CDC or WHO standard has a discriminatory advantage over the 99(th) percentile for identifying severely obese children at increased cardiometabolic risk, particularly under 10 years of age.
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