| BackgroundWith the development of the social economy and the change of lifestyle,obesity has become an important public health problem worldwide.The prevalence of overweight and obesity among children and adolescents aged 6-18 years in China has increased significantly in the past 20 years,with the prevalence of overweight among children increasing from 4.3%in 1991 to 11.7%in 2015,and the prevalence of obesity increasing from 2.4%to 12.7%.It is estimated that if no measures are taken,the prevalence of overweight and obesity in children and adolescents aged 7 and above would reach 28.0%,and the number of overweight and obese children and adolescents would reach nearly 50 million by 2030.Cardiovascular disease(CVD)is the leading cause of death in China,and has brought heavy burden to Chinese people.At present,a number of epidemiological studies have proved that overweight and obesity increase the risk of CVD in adults.Studies have shown that blood wall damage may begin in childhood,and most of the early cardiovascular damages are subclinical.Carotid intima-media thickness(cIMT)is a commonly used subclinical index,and is a sensitive clinical marker of atherosclerosis,closely related to CVD in adulthood.Current findings showed that adult obesity is related to cIMT.However,studies on the relationship between childhood obesity and cIMT are scarce and the results are inconsistent.As for the hazards of obesity,weight loss is an important prevention and treatment measure for adult CVD.Many studies showed that weight loss can reduce the risk of CVD for overweight or obese individuals.A prospective cohort study showed that subjects who were overweight or obese in childhood but had normal weight in early adulthood had a similar risk of incident of high cIMT in adulthood,compared with persistent normal-weight individuals.However,studies on the relationship between weight status changes and cIMT in childhood have not been reported.Objectives1.To analyze the relationship between overweight/obesity and the level cIMT,and the relationship between overweight/obesity and high cIMT in children.2.To analyze the relationship between weight status changes and the level of cIMT,and the relationship between weight status changes and high cIMT in children.Subjects and methods1.Study populationData come from "Huantai Childhood Cardiovascular Health Cohort Study(HCCH)".We adopted convenient cluster sampling,and selected a public primary school in Huantai County,Zibo City,including all students in grades 1 to 5 as the subjects.The baseline survey was conducted from November 2017 to January 2018,and a total of 1515 children aged 6-11 years were surveyed.The first follow-up was completed from November 2019 to December.A total of 1243 children aged 8-13 years were investigated.After excluding those with missing variables(sex,age,systolic blood pressure(SBP),and diastolic blood pressure(DBP)screen time,sleep time,physical activity,vegetable and fruit intake),a total of 1492 subjects and 1164 subjects were included at baseline and follow-up respectively,to analyze the relationship between overweight/obesity and cIMT and high cIMT.And After excluding those with missing variables and those with high cIMT at baseline,a total of 1068 subjects were included to analyze the relationship between weight status changes and cIMT and high cIMT in children.2.MeasurementsQuestionnaire surveys,physical measurements and ultrasound examinations were conducted.Questionnaire survey included age,sex,physical activity,sleep time,vegetable and fruit intake,and screen time.Physical examination included height,weight and blood pressure(BP).cIMT was measured by a professional ultrasound doctor through an Philips CX30 Color Doppler ultrasound apparatus.3.DefinitionOverweight and obesity was defined according to the National Health Industry Standard released in 2018-"Overweight and Obesity Screening for School-age Children and Adolescents".High cIMT was defined as cIMT equal to or greater than sex-and age-specific 90th percentile.Weight status change was classified into persistent normal-weight(normal weight at both baseline and follow-up),weight loss(overweight/obesity at baseline and normal weight at follow-up),weight gain(normal weight at baseline and overweight/obesity at follow-up),and persistent overweight(overweight/obesity at both baseline and follow-up).4.Statistical analysisSAS 9.3 was used for data analysis,and P<0.05 was considered to be statistically significant.Continuous variables were expressed as mean ± standard deviation(SD),and categorical variables were expressed as percentages.The generalized estimation equation(GEE)was used to analyze the relationship between BMI and cIMT in the two-point combined data of baseline and follow-up,as well as the relationship between overweight/obesity and high cIMT.A multiple linear model was used to analyze the relationship between BMI and cIMT at baseline and follow-up,and a multiple logistic model was used to analyze the relationship between overweight and obesity and high cIMT.The difference of the continuous variables across different weight status change groups and different cIMT groups was analyzed by variance analysis,and the difference of categorical variables was analyzed by chi-square test.After adjusting for age,sex,physical activity,sleep time,vegetable and fruit intake,screen time,SBP and DBP,the multiple linear regression model was used to analyze the cIMT trend across different weight status change groups,and the multiple logistic regression model was used to examine the relationship between high cIMT and different weight status changes.Results1.Relationships between overweight and obesity and cIMT and high cIMTThe mean of cIMT at baseline and follow-up was 0.469 mm and 0.520 mm,respectively.The results of GEE analysis showed that cIMT was positively correlated with BMI,and the coefficient(95%CI)was 0.007(0.007-0.008).The multiple linear model showed that after adjusting for related variables,cIMT was still positively correlated with BMI among all children,males and females at baseline and follow-up.At baseline and follow-up,there were significant differences in the distribution of cIMT between normal weight,overweight and obesity groups in the all population,boys and girls(P<0.001),and cIMT in obesity group>cIMT in overweight group>cIMT in normal weight group.The results of GEE analysis showed that after adjusting for the related variables,overweight and obesity were positively correlated with high cIMT,and the coefficients(95%CI)were 1.263(0.796-1.730)and 2.838(2.467-3.209),respectively.The multiple logistic model showed that after adjusting for the related variables,the overweight and obese children at baseline had an increased risk of high cIMT,with OR values(95%CI)of 347(1.79-6.75)and 20.31(12.07-34.18),respectively.Subgroup analysis by sex showed that overweight and obese boys and girls had an increased risk of high cIMT compared with normal-weight children.At follow-up,the relationship between high cIMT and overweight and obesity was similar to that of the baseline.2.Relationship between the change of body weight status and the level of cIMTAfter adjusting for related variables,the cIMT values were 0.505 mm in the persistent normal weight group,0.519 mm in the weight loss group,0.523 mm in the weight gain group,and 0.543 mm in the persistent overweight group(trend P<0.001),respectively.After adjusting for age,sex,screen time classification,exercise classification,vegetable and fruit intake classification,sleep time,SBP and DBP,the risk of high cIMT in children with weight gain and persistent overweight/obesity increased compared with children with persistent normal weight,and the OR(95%CI)values were 2.74(1.12-6.69)and 8.22(4.96-13.61),respectively.In contrast,there was no statistically significant difference in the risk of high cIMT in the weight loss group compared with that in the persistent normal weight group.(OR:1.03,95%CI:0.24-4.55).Conclusions1.The levels of cIMT and the risks of high cIMT in the overweight and obese group were higher than that in the persistent normal weight group.2.The level of cIMT and the risks of high cIMT in weight gain group and persistent overweight group were higher than that in the persistent normal-weight group.In contrast,there was no increased risk of high cIMT in the weight loss group compared with that in the persistent normal weight group.Our findings highlight the importance of keeping normal weight during childhood,in order to prevent vascular structure damage. |
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