Association Of Change In Blood Pressure Status With Left Ventricular Hypertrophy During Childhood

BackgroundAlong with the epidemic of pediatric overweight and obesity as well as unhealthy lifestyles,pediatric elevated blood pressure(BP)has become an important public health issue.The China Health and Nutrition Survey showed that the prevalence of elevated BP in children and adolescents aged 7 to 17 years in China increased from 7.0%in 1991 to 11.7%in 2015,according to the 2018 Chinese Hypertension Prevention and Treatment Guideline reference.Currently,cardiovascular disease(CVD)is the leading cause of death in China,with its prevalence and mortality are at a rising stage.Evidence from previous cohort studies has shown that elevated BP in childhood could increase the risk of CVD in adulthood.Left ventricular hypertrophy(LVH)is a subclinical cardiac marker as well as an important risk factor of cardiovascular events.According to the American Academy of Pediatrics(AAP)guideline on hypertension in children and adolescents,LVH is listed as the most common early target organ damage of pediatric hypertension.On the other hand,the degree of LVH in children and adolescents is generally mild.If early intervention and treatment are given for controlling pediatric elevated BP,LVH might be effectively reversed in childhood.A prospective cohort study showed that elevated BP in childhood but normal BP in adulthood might not increase the risk of high left ventricular mass index(LVMI)in adulthood.Recent evidence has shown that elevated BP was associated with LVH in children and adolescents.However,few studies have examined the association of change in BP status with LVH in childhood.Objectives1.To examine the association of BP level with LVH during childhood2.To examine the association of change in BP status with LVH during childhood.Subjects and methods1.Study populationData were extracted from the baseline and the first follow-up survey of "Huantai Childhood Cardiovascular Health Cohort Study".At baseline,from November 2017 to January 2018,a total of 1515 children aged 6 to 11 years from a public primary school in Huantai County,Zibo City,Shandong Province were selected using a convenient clustering sampling method.From November to December 2019,a total of 1243 children were followed up.Participants were invited to fill in a standardized questionnaire and undergo physical examinations and ultrasound measurements at both baseline and follow-up.After excluding those with missing data on age,sex,height,weight,systolic blood pressure(SBP),diastolic blood pressure(DBP),sleep time,physical activity,intake of soft drinks,intake of fruits and vegetables,and LVMI as well as those with LVH at baseline,a total of 1072 children were included to examine the association of change in BP status with LVH during childhood.2.MeasurementsSex,age,intake of fruits and vegetables,intake of soft drink,physical activity,and sleep time were obtained by standardized questionnaires.Height,weight,SBP,and DBP were measured by anthropometric measurements.Using Philips CX30 ultrasound measurements to obtain left ventricular end-diastolic diameter(LVDD),interventricular septal thickness(IVST),and left ventricular posterior wall thickness(LVPWT).3.DefinitionElevated BP was defined as SBP and/or DBP≥ sex-,age-,and height-specific 95th percentile values according to the Chinese BP references for children and adolescents.Based on the change in BP status at baseline and follow-up,the change in BP status was categorized into four groups:persistent normal BP(normal BP at both baseline and follow-up);BP decrease(elevated BP at baseline but normal BP at follow-up);BP increase(normal BP at baseline but elevated BP at follow-up);and persistent elevated BP(elevated BP at both baseline and follow-up).LVH was defined as LVMI≥ sex-and age-specific 90th percentile values in this population.Overweight and obesity was defined using the National Health Industry Standard released in 2018.4.Statistical analysisContinuous variables were expressed as mean± standard deviation(x±s)and group differences were compared by analysis of variance.Categorical variables were presented as n(%)and group differences were compared by the chi-square test.Multiple linear analysis was used to analyze the association of elevated BP with LVMI at baseline and follow-up.Logistic regression analysis was performed to analyze the association of elevated BP with LVH at baseline and follow-up.The generalized estimation equation(GEE)was used to analyze the association of elevated BP with LVH.Restricted cubic spline(RCS)analysis was used to assess the dose-response relationship of BP level with LVH at baseline and follow-up.Multiple linear analysis was used to analyze the association of change in BP status with LVMI.Logistic regression analysis was used to analyze the association of change in BP status with LVH.Data analyses were conducted using SAS 9.4.A two-sided P<0.05 was considered statistically significant.Results1.Association of BP with LVMI and LVH during childhoodThe prevalence of elevated BP at baseline and follow-up were 15.2%and 12.0%,respectively.The level of LVMI and the prevalence of LVH were significantly different between normal BP and elevated BP groups at baseline and follow-up(P<0.05),children with elevated BP had a higher level of LVMI and proportion of LVH.The result of multiple linear analysis showed that after adjusting for sex,age,intake of fruits and vegetables,intake of soft drinks,physical activity,sleep time,and weight status,elevated BP was not significantly associated with LVMI at baseline(β=0.18,P=0.567).However,elevated BP was positively associated with LVMI at follow-up(β=1.43,P<0.001).The result of Logistic regression analysis showed that after adjusting for potential confounding factors,compared with normal BP,elevated BP was not significantly associated with LVH at baseline[odds ratio(OR)=1.05,95%confidence interval(CI):0.68-1.63].However,elevated BP was associated with LVH at follow-up(OR=2.11,95%CI:1.30-3.41).The result of GEE analysis showed that after adjusting for related confounding factors,elevated BP was positively associated with LVH,with the coefficient(95%CI)being 0.40(0.08-0.72).The result of restricted cubic spline analysis showed that after adjusting for sex and age,the dose-response relationship of SBP and DBP with LVH at baseline and follow-up appeared to be linear(all P for non-linearity>0.05).2.Association of change in BP status with LVMI and LVH during childhoodA total of 1072 participants were included.There were 846,113,72,and 41 children in the persistent normal BP group,BP decrease group,BP increase group,and persistent elevated BP group,respectively.The level of LVMI and the prevalence of LVH were significantly different among four groups(P<0.05),and those were expressed as persistent elevated BP group>BP increase group>BP decrease group>persistent normal BP group.The result of multiple linear analysis showed that after adjusting for sex,age,intake of fruits and vegetables,intake of soft drinks,physical activity,sleep time,and weight status,persistent elevated BP was positively associated with LVMI(β=1.56,P=0.008).However,BP decrease(β=0.17,P=0.637)and BP increase(β=0.76,P=0.096)were not significantly associated with LVMI.The result of Logistic regression analysis showed that after adjusting for potential confounding factors,compared with children with persistent normal BP,those with persistent elevated BP had a higher risk of LVH(OR=2.33,95%CI=1.06-5.13).However,those with BP decrease and BP increase had no significant increased risk of LVH,with OR(95%CI)being 0.83(0.41-1.69)and 1.60(0.80-3.20),respectively.Conclusions1.Elevated BP was associated with LVH during childhood.There was a linear dose-response relationship of SBP and DBP with LVH.2.Persistent elevated BP increased the risk of LVH during childhood.Conversely,children with elevated BP early but normal BP later in childhood might not have an increased risk of LVH.