Association Of Obesity-related Indicators With Elevated Blood Pressure In Children And Adolescents

Objective:Previous studies have shown that obesity was a risk factor for hypertension among children and adolescents,and indexes such as body mass index(BMI),waist circumference(WC),waist-to-height ratio(WHtR),waist-hip ratio(WHR),and skinfold thickness were related with hypertension.In this study,we used data from the China Health and Nutrition Survey(CHNS)to explore the relationship between obesity-related indicators and elevated blood pressure in children and adolescents,and to provide a reference basis for the early prevention of hypertension in children and adolescents.Subjects and Methods:1.Data were from the study of CHNS.The survey was conducted by the University of North Carolina's Rolla State Population Center in collaboration with the National Institute of Nutrition and Food Safety of the China Center for Disease Control and Prevention.Multi-stage stratified cluster sampling method was used to select 9 provinces/autonomous regions such as Guangxi,Jiangsu,Shandong and Heilongjiang.According to the economic construction,the country is divided into six areas,namely,big cities,small and medium-sized cities,first-class rural areas,second-class rural areas,third-class rural areas,and fourth-class rural areas.A total of 10786 children and adolescents(boys:5637,girls:5149)aged 6-17 years surveyed in 1993,1997,2000,2004,2006,2009,2011 and 2015 with complete information of gender,age,and related indicators were included in this study.2.Questionnaires and body measurements were used to collect information.Basic demographic information such as age and gender were obtained from standard questionnaires.Physical measurements included height,weight,hip circumference,WC,systolic blood pressure(SBP),diastolic blood pressure(DBP),and skinfold thickness.Height was measured with calibrated height scales,and weight was measured with calibrated beam scales.WC was measured with nonelastic tape at 1cm above the navel.Hip circumference was measured at the most prominent part of gluteus maximus.Using the skinfold thickness of triceps brachii as the skinfold thickness of the whole body.Mercury sphygmomanometer was used to measure blood pressure(BP).Elevated BP was defined by the Blood Pressure References for Chinese Children Aged 3-17 Years established by Mi Jie et al in 2017.The mean values of the last two measurements(systolic or diastolic)? P95 can be defined as elevated BP.WHtR=WC(cm)/height(cm),BMI=weight(Kg)/height2(m2),WHR=WC(cm)/hip circumference(cm).3.The software of SPSS 22.0 was used for data analysis.Mean±standard deviation(x±s)was used to express continuous variables.The t test was used to compare the differences by genders.N(%)was used to presented categorical variables and chi-square test or fisher exact probability method was used to compare the differences between different groups.P<0.05 indicates that the difference is statistically significant.Correlation analysis was used to measure the correlation between obesity-related indexes and BP.Multivariate linear regression was used to analyze the correlation between obesity-related indicators and DBP and SBP,and Receiver Operating Characteristics(ROC)curve analysis was performed to analyze the predictive value of obesity-related indicators for the occurrence of elevated BP in children and adolescents.Results1.A total of 107886 children and adolescents were included in this study.The prevalence of elevated BP was 13.16%(n=1420),and was 13.36%(n=753)in boys and 12.95%(n=667)in girls,respectively.There was no significant difference between boys and girls(P>0.05).The prevalence of elevated BP among children(6-12 years old)and adolescents(13-17 years old)were 11.39%(n=720)and 15.67%(n=700),respectively,and the difference was significant between children and adolescents(P value<0.05).The prevalence of elevated BP in urban and rural areas among children and adolescents were 13.11%and 13.32%,respectively,and the difference was not significant(P>0.05).2.Compared with girls,BMI,WC,WHtR and WHR of boys were higher(P<0.05),while the thickness of skinfold was lower(P<0.05).Subgroup analysis showed that BMI,WC,and skinfold thickness of adolescent were higher than those of children(P<0.05),while WHR were lower than those of children(P<0.05).3.BMI,WC,WHtR and skinfold thickness were significantly different between normal and abnormal BP groups(P<0.05),but there was no significant difference with WHR(P>0.05).Correlation analysis showed that BMI,WC,WHtR and skinfold thickness were positively correlated with SBP and DBP in boys and girls(P<0.05).4.Multiple linear regression analysis showed that BMI,WC,WHtR and skinfold thickness were the influencing factors of SBP in boys and girls.BMI and WHtR had a higher impact on SBP and DBP in boys and girls.5.ROC curve analysis showed that BMI,WC,WHtR and skinfold thickness had predictive value for elevated BP.And the AUC of BMI was higher(AUC=0.642,Sensitivity=63.3%,Specificity=56.2%).Conclusion1.There were significant differences in the prevalence of elevated BP among children and adolescents by sex and age.2.With the increase of age,BMI,WC,and skinfold thickness increased,while the WHR decreased.3.BMI,WC,WHtR and skinfold thickness were important influencing factors for SBP and DBP of both boys and girls.4.BMI,WC,WHtR and skinfold thickness had predictive value for the occurrence of elevated BP,and the AUC in BMI is higher.