Metabolic syndrome (MetS) is an emerging burden associated with significant morbidity and mortality in children and adolescents. In recent decades, the prevalence of obesity has continually increased both worldwide and in Korea.^1,2 Trends in mean body mass index (BMI) have recently flattened for both boys and girls in northwestern Europe and Asia-Pacific regions, for boys in southwestern Europe, and for girls in central and Latin America.¹ In contrast, the rise in BMI has accelerated for both boys and girls in east and South Asia, and for boys in Southeast Asia.¹ Pediatric obesity is often accompanied by MetS. Consequently, accurate evaluation of obesity in children and adolescents is of significant interest because it may result in adulthood obesity and comorbid conditions such as cardiovascular disease, obstructive sleep apnea, insulin resistance, non-alcoholic fatty liver disease, and dyslipidemia.^3,4

More than half of all obese children have two or more complications. The definition of MetS by the modified criteria of the National Cholesterol Education Program-Adult Treatment Panel III must include at least three of five criteria: central obesity above the 90th percentile, fasting glucose above 110 mg/dL, hypertriglycerides above 110 mg/dL, low high density lipoprotein cholesterol below 40 mg/dL, and hypertension above the 90th percentile or receiving treatment for hypertension.¹ Based on the criteria of the International Diabetes Federation, MetS is a combination of central obesity with the presence of two or more of the other four risk factors.⁵ According to International Diabetes Federation guidelines, children younger than 6 years are excluded from the definition due to limited data for this age group. MetS cannot be diagnosed at the age of 6 to 10 years. However, additional testing should be performed if there is a family history of MetS, type 2 diabetes mellitus, dyslipidemia, cardiovascular disease, hypertension, or obesity.⁶

Most studies are based on baseline BMI measurements to evaluate excessive adiposity in humans. BMI is a limited indicator of pediatric metabolic risk due to the paucity of data in this population.⁷ Waist circumference (WC) and waist-height ratio (WHtR) are helpful measures of central adiposity in both clinical and research settings.⁸ WC has emerged as an index of pediatric adiposity that predicts fat mass as effectively as or better than BMI.⁸ Moreover, WC has been shown to be effective in estimating total adiposity, which is strongly linked to intra-abdominal fat.

Several studies have investigated the prevalence of abdominal obesity in children and adolescents and report that it ranges from 9.7% to 11.5% in Korea.^9-11 Compared with previous studies,^9-11 the prevalence of abdominal obesity increased from 14.71% based on 2022 Korean National Growth Charts (REF2022),¹² 5.95% higher than that of 8.86% based on 2007 Korean National Growth Charts (REF2007).¹³ Furthermore, MetS based on REF2022 had a higher prevalence by both the National Cholesterol Education Program definition (3.9%¹³ by REF2007 and 4.78%¹² by REF2022) and the International Diabetes Federation definition (2.29%¹³ by REF2007 and 3.10%¹² by REF2022). A previous study¹⁴ found that the prevalence of MetS was underestimated at 2.8% in children (6 to 12 years) and 4.8% in adolescents (13 to 18 years).

This study contributed to our understanding of the prevalence of pediatric abdominal obesity and the development of MetS using Korea National Health and Nutrition Examination Survey data over a follow-up period of approximately 14 years (2007 to 2020).¹⁵ The authors compared the prevalence of abdominal obesity and MetS in a database of 21,652 individuals aged 2–18 and 9,592 individuals aged 10–18.¹⁵ The results of previous studies of the prevalence of MetS demonstrate underestimates compared to those based on the Lee et al.¹²

Pediatric abdominal obesity is one of the primary diagnostic criteria for the prevalence of MetS. Therefore, large prospective cohort studies are necessary to understand its prevalence as well as to evaluate and confirm the contribution of MetS. Furthermore, exploration of a potential obesity indicator, the WHtR, should be conducted. The large number of children and adolescents with MetS worldwide demonstrates the urgent necessity for multi-sectoral interventions to minimize the global burden of MetS and factors that contribute to it, such as childhood overweight and obesity.

The authors declare no conflict of interest.