BACKGROUND Metabolic syndrome (MetSyn) in children and adolescence is increasing worldwide; however, its pattern may be different between Asians and Americans. We compare the prevalence and patterns of MetSyn between American and Korean children and adolescents between roughly 1998 and 2007.

METHODS Data from the American and Korean versions of the NHANES (NHANES and KNHANES) were used for this study. The main outcome is prevalence and pattern of MetSyn among participants separately in each country. In each survey, stratified multistage probability sampling designs and weighting adjustments were conducted to represent the entire population. The revised National Cholesterol Education Program criteria were used to define MetSyn.

RESULTS Totals of 934, 1781, and 1690 Americans aged 12 to 19 participated in NHANES 1988-1994, NHANES 1999-2002, and NHANES 2003-2006, respectively; and 1225, 976, 705, and 456 Koreans aged 12 to 19 have participated in KNHANES 1998, 2001, 2005, and 2007. The age-adjusted prevalence of MetSyn in American NHANES decreased from 7.3% to 6.7% and 6.5%, whereas in Korean NHANES there was an increase from 4.0% to 5.9%, 6.6%, and 7.8% in each country's respective study. Increases in dyslipidemia and abdominal obesity contributed to the increased prevalence in Korea, whereas in the United States, decreases in low high-density lipoprotein cholesterolemia and high blood pressure contributed to a decreased prevalence.

CONCLUSIONS Considering different phenotype changes, different approaches should be conducted at the national level to reduce the burden and consequences of MetSyn between Korea and the United States.