| BackgroundWith the economic development and the prevalence of unhealthy lifestyles,cardiovascular disease(CVD)has become the leading cause of death in China.There are multiple risk factors for CVD development,particularly for obesity.Recently,obesity in children and adolescents has been a major public health issue.The latest figures show that in 2015,about 100 million children and adolescents were obese globally,with the largest number in China(about 15.3 million).From 1985 to 2014,the overweight prevalence in children aged 7 years or older in China increased from 2.1%to 12.2%,and the obesity prevalence increased from 0.5%to 7.3%.The corresponding number of overweight and obese children increased from 6.15 million to 34.96 million.The carotid intima-media thickness(cIMT)is an important marker of atherosclerosis.Many studies have shown that vascular structural changes and endothelial dysfunction have already occurred in obese children.However,it is still unclear which obesity index(such as body mass index,waist circumference and waist-to-height ratio)has a greater screening effect on vascular damage.Therefore,the purpose of this paper is to evaluate the screening effect of body mass index(BMI),waist circumference(WC),and waist-to-height ratio(WHtR)on high cIMT in children,so as to choose more sensitive screening index for high cIMT in childhood,providing scientific evidence for prevention and control of childhood cardiovascular disease risk factors.Objectives1.To examine the prevalence of obesity among children aged 7 to 11 years old screened by different definitions based on BMI,WC,and WHtR.2.To compare the effect of different definitions of BMI,WC,and WHtR for screening high cIMT in children.Subjects and MethodsSubjectsData were from the baseline survey of "Children's Cardiovascular Health Cohort",performed from November 2017 to January 2018.A primary school from Huantai county in Zibo city was selected.All students who were willing to participant from the first grade to the fifth grade were recruited as study subjects.Informed written consent was obtained from their parents.A total of 1273 children aged 7 to 11 years old were included in this study.MethodsA questionnaire was used to collect the basic information of the study subjects(name,age,and class,etc),information on early life.Anthropometric measurements(height,body weight and waist circumference)and cIMT were measured by trained examiners.The performance of BMI,WC and WHtR for screening high cIMT was examined.Statistical analysisSAS 9.3 was used for data analysis.Continuous data were presented by mean and standard deviation.A t-test was used for comparison between groups.The receiver operating characteristic(ROC)curve analysis were used to assess the accuracy of screening effect of BMI,WC,and WHtR on high cIMT.We calculated the area under the curve(AUC),the sensitivity,specificity,positive predictive value and negative predictive value.Binary logistic regression analysis was used to compare the effect of BMI,WC,and WHtR on screening high cIMT(adjusted for age and gender).P<0.05 indicates that the difference is statistically significant.Results1 The detection rates of obesity by each adiposity indexObesity detection rates by BMI standard,WC standard and WHtR standard was 22.9%,31.0%,and 24.7%,respectively.The obesity rates detected by different standards showed the similar trend.All rates increased first and decreased latter and the highest rate appeared in 9 years old group.2 Performance of different adiposity indices for screening high cIMTThe AUC of BMI-Z score,WC-Z score and WHtR-Z score for screening high cIMT was 0.86,0.88 and 0.85,respectively.For all adiposity indices,the accuracy for screening high cIMT in boys was higher than that of girls,and that in older group(10-11 years old)was higher than that of younger group(7-9 years old).The effect of combined indices for screening high cIMT was similar to each adiposity index.3 Risk of high cIMT predicted by different adiposity indicesThe risk of high cIMT predicted by BMI,WC,and WHtR standard was 14.29,18.68,and 14.80,respectively.There was a marginal difference between the obesity identified by WC,BMI and WHtR sandard screening of high cIMT.Overall,for each adiposity index,the risk in boys were higher than that in girls,and the OR of higher age group(10 to 11 years old)is greater than that of the lower age group(7 to 9 years old).Conclusions1 The obesity detection rate based on definitions of BMI,WC and WHtR was 22.9%,31.0%and 24.7%,respectively,indicating that childhood obesity is prevalent.2 The values of AUC of BMI,WC and WHtR were 0.86,0.88 and 0.85,respectively,indicating that the effect of the three adiposity indices was similar for screening high cIMT.3 Definitions based on BMI and WC should consider gender and age,while WHtR as an indicator of abdominal obesity has only one single cutoff(0.50)which is easy to remember.Then,WHtR can be used as a simple index for screening vascular damage in children. |
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