Evaluation Of Simplified Screening Methods For Elevated Blood Pressure In Children

1 BackgroundWith increase in prevalence of unhealthy lifestyle and childhood obesity,age at onset of hypertension is decreasing,and hypertension in childhood has become a public health issue in China.It has been demonstrated that elevated blood pressure tracked from childhood to adulthood,i.e.elevated blood pressure in children could keep into adulthood.In addition,elevated blood pressure in childhood can increase risk of early target organ damage and cardiovascular disease in adulthood.Therefore,early detection of elevated blood pressure in childhood and timely and effective interventions play important roles in reducing the huge burden of cardiovascular disease in adulthood.At present,elevated blood pressure in children is defined as systolic blood pressure and/or diastolic blood pressure equal to or higher than 95th gender-,age-and height-specific percentiles.There are more than 400 thresholds that are inconvenient to be applied in practices.Considering the complexity of the references,some simplified screening methods have been proposed,including blood pressure-to-height ratio,mathematical formulas,simplified sex-and age-specific cutoffs and height-specific cutoffs.However,most screening methods were based on the complex blood pressure references for American children.Therefore,it is necessary to establish a simplified screening method based on the updated blood pressure references for Chinese children to facilitate the prevention and treatment of elevated blood pressure in children and adolescents in China.To assess the performance of simplified methods,the complex standard is used as golden standard,and the values of sensitivity,specificity,positive predictive value,negative predictive value and kappa index are calculated.However,the aim of establishing simplified screening methods is to identify children with elevated blood pressure and to prevent the changes of subclinical cardiovascular structure and function.Therefore,it is important to evaluate the effect of simplified screening methods through linking the simplified standard to the health outcome in children and adolescents.2 Objectives2.1 We developed four simplified screening methods based on the "updated blood pressure references for Chinese children aged 3?17 years"(the 90th and 95th age-,sex-and height-specific percentiles of blood pressure)in 2017.Compared with the complex standard,the effect of the four simplified screening methods was assessed in our study population.2.2 We investigated the association of elevated blood pressure identified by the complex reference and four simplified screening methods with high carotid intima-media wall thickness(cIMT).In addition,compared with the complex standard,we.assessed the effect of the 4 simplified methods for screening high cIMT.3 Subjects and methods3.1 Selection of subjectsData were obtained from the baseline survey of "Children's Cardiovascular Health Cohort" conducted in Huantai County,Zibo city of Shandong Province from November 2017 to January 2018.The students from 1st grade to 5th grade in Chengnan primary school who agreed to participate in the survey with written informed consents were selected.Finally,a total of 1506 children aged 6 to 11 years old participated in questionnaire survey,anthropometric measurements and ultrasonic measurements.3.2 Collection of informationThe basic information of the subjects was collected by self-reported questionnaire(e.g.the information of age,gender and so on).Height and weight were measured using the domestic HGM-300 ultrasonic electronic instruments.The HEM-7012(Omron)was used to measure blood pressure.Blood pressure was measured after resting 10 to 15 minutes in a quiet room,evacuating the bladder and without strenuous exercise for at least half an hour.Blood pressure was measured at least three times and the differences between any two values should not exceed 10 mmHg.The mean values of the last two measured values were used in our study.Ultrasonic examination of cIMT was measured by the same specialist.3.3 Statistical analysisData were analyzed using SAS 9.4 software.Differences in continuous variables and categorical variables between groups were compared by t test,?2test or Fisher's exact probability method,respectively.Compared with the complex standard,4 simplified methods were used to identify elevated blood pressure in childhood.Paired ?2 test was used to compare the differences in detection rates among four definitions.Kappa values were used to evaluate the agreement between the simplified methods and complex standard.In addition,compared to the complex standard,area under the curve(AUC),sensitivity,specificity,positive predictive value,and negative predictive value of four simplified methods were calculated,to evaluate the performance of four simplified methods using receiver operating characteristics curve(ROC)analysis.The association of elevated blood pressure defined by four simplified methods and complex standard with high cIMT was analyzed using Logistic regression analysis.4 Results4.1 Elevated blood pressure assessed by the complex standard and simplified methodsPaired ?2 test showed that there was no significant difference between the prevalence of elevated blood pressure identified by the sex-and age-specific method or the height-specific method and that identified by the complex standard(P>0.05).However,differences between the age group-specific method,formula method and complex standard were statistically significant(P<0.001).For screening pre-elevated blood pressure,values of AUC of the sex-and age-specific method,the formula method and the height-specific method were 0.92,0.93 and 0.94,respectively,which were higher than that of the age group-specific method(0.88).The kappa values of the sex-and age-specific method and the height-specific method were 0.85 and 0.89,respectively,suggesting the good consistency with the complex standard.However,the kappa values of the formula method and the age-specific method were 0.79 and 0.72,respectively,which were not satisfactory.The values of sensitivity,specificity,positive predictive value and negative predictive value of the sex-and age-specific method were 89.3%,95.5%,89.1%and 95.6%,respectively.The values of sensitivity,specificity,positive predictive value and negative predictive value of height-specific method were 91.1%,97.5%,93.7%and 96.4%,respectively.The screening effect of four simplified methods was similar stratified by age and sex.For screening elevated blood pressure,the values of AUC of the sex-and age-specific method,the formula method and the height-specific method were 0.92,0.93 and 0.92,respectively,which were higher than that of the age-specific method(0.88).The kappa values of the sex-and age-specific method and the height-specific method were 0.85 and 0.85,respectively,suggesting good consistency with the complex standard.The values of sensitivity,specificity,positive predictive value and negative predictive value of the sex-and age-specific method were 86.1%,97.9%,88.0%and 97.5%,respectively.The values of sensitivity,specificity,positive predictive value and negative predictive value of the height-specific method were 85.2%,98.3%,89.9%and 97.4%,respectively.The screening effect of four simplified methods was similar stratified by age and sex.4.2 Performance of four simplified methods for screening high cIMTAfter adjusted for age and sex,there was significant association between pre-elevated blood pressure and elevated blood pressure identified by complex standard with risk of high cIMT(pre-elevated blood pressure:OR=2.06,95%CI:1.47?2.88;elevated blood pressure:OR=2.80,95%CI:1.93-4.06).After further adjustment for BMI,no significant association was found between pre-elevated blood pressure and high cIMT(OR=0.84,95%CI:0.56-1.27).Similarly,no significant association was found between elevated blood pressure and high cIMT(OR=1.27,95%CI:0.81?2.00).After adjusted for age and sex,there was significant association between pre-elevated blood pressure identified by four simplified methods with high cIMT(the sex-and age-specific method:OR=2.51,95%CI:1.80-3.51;the age-specific method:OR=2.55,95%CI:1.80?3.60;the formula method:OR=2.09,95%CI:1.50?2.92;the height-specific method:OR=1.97,95%CI:1.41?2.77).Similarly,significant association was found between elevated blood pressure identified by four simplified methods and high cIMT(the sex-and age-specific method:OR=3.10;95%CI:2.14?4.49;the age-specific method:OR=2.84,95%CI:1.97?4.10;the formula method:OR=2.35,95%CI:1.65?3.36;the height-specific method:OR=2.62,95%CI:1.79-3.85).However,after further adjustment for BMI,there were no statistically significant association of both pre-elevated blood pressure and elevated blood pressure with high cIMT(P>0.05).5 Conclusions(1)The four simplified screening methods performed well for the identification of pre-elevated blood pressure and elevated blood pressure,compared with the complex standard.However,the sex-and age-specific method and the height-specific method performed better than other two methods.(2)Compared to the complex definition,four simplified methods performed similarly in screening high cIMT.(3)Compared to the sex-and age-specific method,the height-specific method is easily to use with less categories and cutoffs.Therefore,the height-specific method is recommended to screen elevated blood pressure in children.