[Comparison of different definitions on metabolic syndrome in obese children]

To compare the prevalence rates of metabolic syndrome (MS) in obese children, according to three commonly used 'Pediatric MS definitions': (1) the International Diabetes Federation (IDF), (2) Cook, et al, and(3)da Silva, et al, in order to choose an appropriate one for the Chinese obese children. It was also intended to assess the variances of American or Chinese cutoff values on MS prevalence.

A retrospective study was performed in obese children from Obesity Outpatient Service Program from January 2004 to December 2008. Subjects were eligible if they met the following criteria: (1) aged 7 to 18 years, (2) with no following conditions as hereditary endocrine or metabolic diseases, secondary obesity, hepatic or renal disease, using medication that alters blood pressure or glucose or lipid metabolism etc., (3) data were complete on the variables of interest. Height, weight and waist circumference, systolic and diastolic blood pressure, fasting lipid profiles, blood sugar and insulin were measured. Insulin resistance was evaluated by homeostasis model assessment (HOMA). American or Chinese cutoff values were used to identify central obesity and hypertension. The prevalence rates of MS under three definitions were calculated and compared by Kappa test to determine the degree of agreement.

136 patients with 103 males and 33 females were enrolled in the study. According to the American cutoff value, 19.2%, 34.6%, 52.9% of the subjects were classified as MS under definitions of IDF, Cook, et al, da Silva, et al respectively, matching well with 19.2%, 43.4%, 58.1% when the Chinese cutoff value was used (Kappa = 1, 0.79, 0.90). The degrees of agreement according to the Kappa statistics between Cook, et al and da Silva, et al (0.52, American cutoff value/0.51, Chinese cutoff value) were better than the others (0.24 - 0.4). Children who were diagnosed as MS under the definitions of Cook, et al. or da Silva, et al. appeared to have had serious insulin resistance when compared to those without MS.

Prevalence of the metabolic syndrome appeared to be high among the obese pediatric outpatients, which was probably due to the definition being chosen. The use of definitions provided by Cook, et al and da Silva, et al might be more suitable for MS diagnosis in obese children in the outpatient department, if insulin resistance was under consideration. Both American and Chinese cutoff value could be used for MS diagnosis in the Chinese obese children.