The Prevalence Of Metabolic Syndrome And Its Components And The Appropriate Cut-offs Of Body Mass Index Among Children And Adolescents

Objective:①To estimate the prevalence and distribution of metabolic syndrome among children and adolescents in Hezhou city in Guangxi.②To identify the appropriate cut-offs of body mass index(BMI)for children and adolescents in Guangxi as a component of metabolic syndrome.Methods:Male and female respondents aged 6 to 18 years(n=5985).The prevalence of metabolic syndrome and its components were analyzed with different definitions or criteria.The sensitivity,specificity and distance in ROC curve by different cut-offs of BMI for identifying one,two or more risk components of metabolic syndrome were estimated to fred the cut-off point for children and adolescents with the shortest distance in ROC curve.Results:①The prevalence of impaired fasting glucose(5.6≤FBG＜7.0mmol/L) was 0.46%,impaired glucose tolerance 0.54%,overweight 5.25%,obesity2.03%, hypertension 16.80%,high triglycerides(TG)14.68%,low HDL cholesterol 6.74%,high LDL cholesterol 6.28%,high total cholesterol(TC)6.25%,high uric acid(UA)2.07%,respectively.②The rates of impaired glucose tolerance (p＜0.001),high TG(p＜0.001),low HDL cholesterol(p＜0.001),high LDL cholesterol(p＜0.05),high TC(p＜0.05)and high UA(p＜0.05)were higher in high school boys and girls than that in elementary school boys and girls,but it is reversed for overweight(p＜0.001),obesity(p＜0.001)and hypertension (p＜0.001).③Overweight or obese children and adolescents had higher prevalence of hypertension(p＜0.001)and high triglycerides(p＜0.05)than nonobese children and adolescents.Overweight or obese children and adolescents had higher levels of blood pressure,triglycerides,fasting serum insulin,insulin resistance index(homeostasismodel assessment),TC,UA and lower HDL cholesterol than nonobese children and adolescents(p＜0.001 or p＜0.05).④BMI≥the age- and sex-specific 97th percentile corresponded to the shortest distance in ROC curve,namely,at these cut-offs,the rates of false positive and false negative for identifying clustering of risk components were the minimum.⑤The prevalence of hypertension with the criterion of systolic or diastolic blood pressure≥the age- and sex-specific 90th percentile was higher than that with the criterion of by calculation in a formula(16.8%vs 2.74%,p＜0.001).⑥The prevalence of IFG2(5.6≤FBG＜7.0mmol/L)was higher than that of IFG1(6.1≤FBG＜7.0mmol/L).The rate of IFG2 adjusted by age and gender was 0.61%,while IFG1 was 0.11%.⑦We suggested abnormalities of components of metabolic syndrome as follow:a)BMI≥the age- and sex-specific 97th percentile;b)blood pressure≥the age- and sex-specific 90th percentile;c)fasting blood glucose≥5.6mmol/L,or 2-h postchallenge glucose≥7.8mmol/L;d)TG≥1.24mmol/L;e)HDL cholesterol≤1.04mmol/L.Subjects who met at least three of the five criteria were classified as having a metabolic syndrome.⑧The prevalence of metabolic syndrome among children and adolescents aged 6 to 18 years was 0.31%with using the difenition in this paper.It is higher in obesity children and adolescents than in nonobesity children and adolescents.Conclusion:①There is prevalence of metabolic syndrome and its components among children and adolescents in Hezhou city in Guangxi,especially in obese children and adolescents.②BMI≥the age- and sex-specific 97th percentile is the appropriate cut-offs for children and adolescents in Guangxi as a component of metabolic syndrome.③If a child had three or more of the following components,metabolic syndrome could be defined:BMI≥the age-and sex-specific 97th percentile,SBP or DBP≥the age- and sex-specific 90th percentile,TG≥1.24mmol/L,HDL-C≤1.04mmol/L and fasting blood glucose 5.6mmol/L or 2-h postchallenge glucose≥7.8mmol/L.This recommendation need further confirmed in representative sample of Chinese population.