Association Of Elevated Blood Pressure With High Carotid Intima-Media Thickness And Left Ventricular Hypertrophy In Children

BackgroundCardiovascular diseases(CVD)have caused a huge disease burden on Chinese residents’ health.The China Cardiovascular Health and Disease Report 2019 pointed out that the number of people suffering from CVD in China is about 330 million,of which 245 million are hypertensive patients which may cause severe challenges on the prevention and control of CVD.At the current stage,with the prevalence of unhealthy lifestyles such as high-salt diets and insufficient physical activity,hypertension is epidemic among children and adolescents,which may not only lead to early target organ damage(TOD)such as high carotid intima-media thickness(cIMT)and left ventricular hypertrophy(LVH)in children but also increase the risk of incidence rate of CVD in adulthood.cIMT is a subclinical index to evaluate the early damage of vascular structure in children,and it is related to early changes of coronary atherosclerosis.LVH is an important indicator reflecting changes in heart structure and it is closely related to the occurrence of heart diseases,and LVH can be measured by the left ventricular mass index(LVMI).However,cardiovascular damage in childhood is mostly structural changes,if children’s blood pressure(BP)can be routinely measured and children with hypertension can be screened in time and taken active and effective preventive measures,it would help reverse the risk of childhood early TOD and reduce the burden of adults CVD,which has important public health significance.In recent years,the reference for children’s elevated BP has been updated continuously and has become more standardized and scientific.The latest references for elevated BP in Chinese children mainly including Mi Jie’ team BP reference based on gender,age,and height percentile for children and adolescents aged 3 to 17 in China,this BP reference was written in 2018 Chinese Guidelines for the Management of Hypertension(hereinafter referred to as "Guideline Reference"),Ma Jun’ team formulated Screening Thresholds for High Blood Pressure in Children and Adolescents from 7 to 18 Years Old,and this BP reference was issued as China’s health industry references in 2018(hereinafter referred to as "Industry reference").However,previous studies based on the above two latest references have not been determined the association of elevated BP with high cIMT and LVH in children,and related conclusions are not consistent.Objectives1.To analyze the association of elevated BP with the level of cIMT and LVMI and the detection rate of high cIMT and LVH in children according to two latest Chinese BP references.2.To analyze the association of elevated BP with high cIMT and LVH according to two latest Chinese BP references.Subjects and methods1.SubjectsThis study relied on the baseline survey of "Huantai Childhood Cardiovascular Health Cohort Study(HCCH)".A convenient cluster sampling method was used to conduct a cross-sectional survey from November 2017 to January 2018 in a primary school.1515 children aged 6 to 11 years old were included in this study.All participants were invited to participate in physical examination,questionnaire survey and ultrasound examination in the baseline survey.A total of 1431 children aged 6-11 years with complete information on all variables were included in this study.Our study obtained the written informed consent from all included children and their parents and,were approved by the ethics committee of the School of Public Health,Cheeloo College of Medicine,Shandong University(Approval number:20160308).2.MethodsPhysical examination included height,weight,and BP,and Body Mass Index(BMI)was calculated.Participants completed the standardized questionnaire on demographic characteristics,eating habits,and lifestyles.The cIMT and LVMI were measured by the CX30 color Doppler ultrasound diagnostic apparatus.3.Definition1.High normal BP and elevated BP were defined according to Guideline reference and Industry reference.Because the Industry reference did not provide the threshold value of high normal BP and elevated BP for 6-year-old children,the definition was replaced by the Guideline reference.The two BP references for children were all defined high normal BP as SBP and/or DBP≥ P90 and<P95(or≥120/80 mmHg)for sex-,age-,and height-,and elevated BP was defined as SBP and/or DBP≥P95 for sex-,age-,and height-.2.Overweight and obesity were defined according to the screening reference for overweight and obesity of school-age children and adolescents issued by the National Health Commission of the People’s Republic of China in 2018(WS/T 586).3.High cIMT was defined as the level of cIMT≥age-and sex-specific 90th of this population since there are no uniform references for high cIMT in Chinese children.4.LVH was defined as the LVMI≥age-and sex-specific 90th of this population since there are no uniform references for LVH in Chinese children.4.Statistical analysesStatistical analyses were performed using SAS version 9.4.Continuous variables approximately normal distribution were represented as x±s and the independent sample t-test was used to compare the differences between the two groups,the categorical variable data is represented by the composition ratio/percentages(%),and the χ2 test was used to compare the differences between the groups.The detection rates of high normal BP and elevated BP in children according to two BP references were tested for consistency,and the weighted kappa(kw)value was calculated.Trendχ2 test was used to analyze the changing trend of the detection rate of high cIMT and LVH with BP..Difference analysis was used to compare the differences in cIMT and LVMI levels between different BP groups.The logistic regression model was used to analyze the association of the BP status of children according to two BP references with high cIMT and LVH.Adjust gender,age,sleep time,screen time,physical activity,vegetables and fruits intake,carbonated beverage intake,overweight and obesity,and other related covariates.All statistical tests were two-sided,the level of significance was P values<0.05.Results1.Consistency test of the detection rate of high normal BP and elevated BP according to two BP referencesA total of 1431 children aged 6 to 11 years were included in this study.Boys were accounted for 53.3%.The detection rates of high normal BP and elevated BP were 14.0%and 15.0%respectively according to Guideline reference,and the detection rates of high normal BP and elevated BP were 13.1%and 11.0%respectively according to Industry reference.The results of the Kappa consistency test showed that the high normal BP and elevated BP according to two BP references were moderately consistent in 6-11 years children among all sex and ages(All kw>0.80,all P value<0.001).2.Covariance analysis of cIMT and LVM levels in different BP groups according to two BP referencesAfter adjusting potential covariates such as sex,age,sleep time,screen time,physical activity,vegetables and fruits intake,carbonated beverage intake,overweight and obesity,the results showed that there was a statistically significant difference in cIMT levels across different BP groups(P<0.001),and the cIMT level of high normal BP and elevated BP groups were higher than normal BP group according to Guideline reference and Industry reference(Guideline reference:elevated BP group:0.476mm,high normal BP group:0.468mm,normal BP group:0.467mm;Industry reference:elevated BP group:0.474mm,high normal BP group:0.470mm,normal BP group:0.468mm,all P values<0.001).After adjusting the above potential covariates,the results showed that there is a statistically significant difference in LVMI of different BP groups based on two reference(P<0.001).and the LVMI level of elevated BP groups were higher than normal BP group according to two reference(Guideline reference:normal BP group:28.39g/m2.7,high normal BP group:28.49g/m2.7 and elevated BP group:28.61g/m2.7;Industry reference:normal BP group:28.36g/m2.7,high normal BP group:28.30g/m2.7 and elevated BP group:29.11g/m2.7,P values<0.001).3.Comparison of the detection rate of high cIMT and LVH in different BP groups according to two BP referencesBased on the Guideline reference,the results showed with the change of BP status,the detection rate of high cIMT is increased(normal BP group:6.2%,high normal BP group:10.0%and elevated BP:20.6%,Ptrend<0.001).The results of the Industry reference were similar to the Guideline reference(normal BP group:9.1%,high normal BP group:8.6%and elevated BP:24.2%,Ptrend<0.001).According to Guideline reference,the results showed that with the change of BP status,the detection rate of LVH is increased(normal BP group:8.2%,high normal BP group:14.0%and elevated BP:14.0%,Ptrend=0.002).The results of the Industry reference were similar to the Guideline reference(normal BP group:8.3%,high normal BP group:13.4%and elevated BP group:16.6%,Ptrend<0.001).4.Logistic regression analysis of high cIMT and LVH in different BP groups according to two referencesAfter adjusting potential covariates such as sex,age,sleep time,screen time,physical activity,vegetables and fruits intake,carbonated beverage intake,overweight and obesity,compared with the normal BP group,there is a statistically significant association between high cIMT and elevated BP according to two references(Guideline reference:OR=1.69,95%CI:1.10～2.60;Industry reference:OR=2.00,95%CI:1.27～3.16,all P values<0.05).After adjusting sex,age,sleep time,screen time,physical activity,vegetables and fruits intake and carbonated beverage intake,the result shown that there is a statistically significant association of LVH with elevated BP according to two references(Guideline reference:OR=1.83,95%CI:1.17～2.86;Industry reference:OR=2.18,95%CI:1.36～3.52;all P values<0.05);however,after further adjusting overweight and obesity,there was not a statistically significant association of LVH with elevated BP according to two references(Guideline reference:OR=1.13,95%CI:0.71～1.81:Industry reference:OR=1.37,95%CI:0.83～2.25,all P values>0.05)Conclusions1.The levels of cIMT and LVMI,and the detection rate of high cIMT and LVH of children in elevated BP groups were higher than normal BP groups according to two BP references.2.The attack risk of high cIMT and LVH in children with elevated BP are increased according to two BP references.