Performance Of Simplified Tables Based On Height Percentage For Screening Elevated Blood Pressure And Hypertension In Children And Adolescents

BackgroundRecently,with the epidemic of unhealthy lifestyle and overweight and obesity among children and adolescents,the onset of hypertension is becoming younger and younger.Elevated blood pressure(BP)in children has become a serious public health problem.Although elevated BP in childhood generally does not have significant clinical symptoms,some children with elevated BP have already had early target organ damage.At the same time,high BP in children and adolescents will increase the risk of hypertension and cardiovascular disease in adulthood.Therefore,routine and effective screening of childhood BP to identify of elevated and high BP early in childhood,and effective strategy and measures are essential to inhibit the rising trend of hypertension and reduce the burden of cardiovascular disease in China.In 2017,the American Academy of Pediatrics updated the clinical practice guidelines for screening and management of high BP in children and adolescents(here after referred to as the"AAP guideline").Similar to the Fourth BP Report for children and adolescent in the United States released in 2004,the BP reference standard(here after referred to as the"AAP standard”)proposed by the AAP guideline include more than 900 BP cutoff's based on sex,age and height,which are too complex and cumbersome to carry out,especially not conductive in large-scale screening programs such as school physical exams,or for non-professionals such as students or parents to conduct BP self-monitoring of abnormal BP.In order to carry out early screening of children's BP better,the AAP guideline recommended a simplified P90 BP table based on sex,age,and the fifth height percentile(here after referred to as the"simplified AAP table")for screening elevated BP in children aged 1-12 years;the thresholds of elevated BP for adolescents equal to or over 13 years of age were set directly at 120/80mmHg.However,previous studies have shown that the sensitivity of AAP BP simplified table can reach 100%because of the threshold value corresponding to the lowest height percentile(P5),but the specificity is low,which will lead to a large number of false-positive patients,so the performance of the simplified AAP table might not be ideal.Our team evaluated and verified the screening performance of simplified BP tables by different height percentiles based on the AAP standard.The results showed that the simplified BP table base on higher height percentile(e.g.the 75th percentile)had less false negative and false positive children,which is more practical when used in screening in schools or communities.However,the simplified method is based on the AAP standards,it may not be applicable to Chinese children and adolescents.In 2017,Ma Jun's team proposed the elevated BP screening standard for Chinese children and adolescents aged 7-17 years based on sex,age and height percentile.This standard was issued as the health industry standards in China(here after referred to as'Industry Standard')in 2018 by National Health Commission.The Industry Standard is also a complex one for school health and child health practice based on sex,age and height with more than 700 BP thresholds.Therefore,it is necessary to establish a simplified method to operate easily based on the Industry Standard.The purpose of this study is to simplify the Industry Standard of BP for pediatrics,and to evaluate the performance of those different simplified BP tables using the survey data of Jinan branch center from the 12th Five Year National Science and Technology Support Program-'Early warning,diagnosis and treatment of cardiovascular disease in children'.Using the China Health and Nutrition Survey(CHNS)data as a verification database to verify the simplified BP table to evaluate the applicability and generalization of the simplified tables in different populations,then we can carry out the prevention and treatment of hypertension in Chinese children and adolescents better.Objectives(1)Eight simplified BP tables by different height percentiles were extracted.Using the Industry Standard as the gold standard,the screening performance of different simplified BP tables were evaluated based on Jinan Data.(2)Using the 2009-2011 data from nine provinces and cities in China to conduct extrapolative validation to further evaluate the application of the best BP simplified table among different populations.Subjects and methods1.The research data is derived from the survey data of the Jinan Sub-center of the 12th Five Year National Science and Technology Support Program-'Early warning,diagnosis and treatment of cardiovascular disease in children',which was carried out from 2012 to 2014(here after referred to as the"Jinan data").In this study,four middle-level non-boarding public primary and secondary schools including 2 primary schools,1 junior high school and 1 senior high school in Jinan city were selected as sampling sites by convenient cluster sampling.All participants were required to have Jinan City household registration or live in Jinan for more than one year and volunteered to participate.Half of the boys and half of the girls were guaranteed,and in the end.A total of 7227 children and adolescents(boys 52.40%)aged 7-17 years with complete information of gender,age,height,weight,waist circumference,systolic and diastolic blood pressure were included in the analysis.The CHNS data is a collaborated multi-center ongoing cross-sectional survey conducted by the Carolina Population Center at the University of North Carolina at Chapel Hill and the National Institute for Nutrition and Health at the Chinese Center for Disease Control and Prevention(here after referred to as the s"CHNS data").Multi-stage cluster sampling was used and 9 provinces or autonomous regions including Guangxi,Heilongjiang,Jiangsu and Shandong were covered in this study.Finally,a total of 2385(boys 53.12%)7-17 years old children and adolescents with complete information on gender,age,height,weight,region,systolic and diastolic blood pressure were included in this study from 2009 to 2011.2.Questionnaires and body measurements were performed in all participated subjects.Jinan data and CHNS data all include gender,age,height,weight,waist circumference,systolic blood pressure(SBP)and diastolic blood pressure(DBP)information.Firstly,the Industry Standard was used as the"gold standard"to determine the elevated BP and hypertension of children and adolescents aged 7-17 years.The screening performance of elevated BP and hypertension of eight simplified BP tables based on different height percentiles were evaluated among children and adolescents in Jinan data.Secondly,the optimal simplified BP tables identified in Jinan data were further validated by CHNS data,so as to evaluate their implementation.3.The software of SAS 9.4 was used for data analysis.Continuous variables were described by mean±standard deviation(x±s),and t-test was used to compare the differences between boys and girls.Categorical variables were expressed by n(%),and the differences between boys and girls were compared by Chi-square test.P<0.05 on both sides indicates that the difference is statistically significant.Using the Industry Standard released in 2018 as the"gold standard".Receiver Operating Characteristic(ROC)curve analysis was used to evaluate the screening performance of sex,age-specific simplified BP tables based on different height percentiles(including<P5,?P5,?P10,?P25,?P50,P75,?P90,?P95).The area under the curve(AUC)and its 95%confidence intervals(CIs),sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV)and Kappa coefficient were calculated respectively.Results1.Comparison of the performance between BP simplified tables based on different height percentilesBased on the Industry Standard to extract simplified BP tables based on 8 different height percentiles(including<P5,?P5,?P10,?P25,?P50,?P75,?P90,?P95)and every simplified table all has 88 BP cutoffs.Taking the Industry Standard as the "gold standard"and using Jinan data as the validation database,we assessed the performance of simplified BP tables based on 8 different height percentiles.For the elevated BP screening,the specificity and PPV increased rapidly(76.92%-100.00%,62.46%-100.00%)with the increase of height percentiles,while the sensitivity and NPV decreased slowly(100.00%-84.39%,100.0%-94.35%).When'the height percentiles were at?P50 or?P75,the AUC value(0.97/0.95),sensitivity(96.86%/91.47%),specificity(96.86%/98.89%),PPV value(92.21%/96.93%)and NPV(98.77%/96.79%)were all high.For the screening of high BP in children and adolescents,the results were similar to those of elevated BP.When the height percentile was above or equal to P50 or P75,the corresponding AUC value(0.95/0.92),sensitivity(94.72%/85.51%),specificity(96.04%/98.22%),PPV(77.06%/87.07%)and NPV(99.23%/97.97%)were also high.Subgroup analysis was performed by age,gender,etc.,and the screening performance were similar to the overall results.2.Validation of simplified BP tablesConsidering that the Jinan data is based on the data of children and adolescents in urban area of Jinan city which implemented by the convenient cluster sampling,the representativeness of the characteristics of the general population might be limited.Thus,we used CHNS data in 2009-2011 with a certain national representative data as verification data to verify the screening performance of simplified BP table based on Pso and P75 height percentiles.The results showed that the simplified BP table based on P50 height percentile was good with high sensitivity(91.40%/85.42%),specificity(99.07%/99.11%),PPV values(95.73%/91.52%)and NPV values(98.06%/98.38%)for screening elevated and high BP respectively.The simplified BP table based on P75 height percentile also performed well for screening elevated BP(sensitivity 86.43%,specificity 99.79%,PPV 98.96%,NPV 97.00%).The results of the subgroups analysis are similar to the overall.Conclusions(1)Simplified BP table based on lower height percentiles(such as the 5th height percentile)can achieve the sensitivity and NPV of 100%,which might be more suitable in clinical practice.However,this simplified BP table can lead to more false positive children(with lower PPV)when screening for elevated and high BP,which will increase the workload of re-diagnosis and create unnecessary psychological burden on children and parents.(2)The simplified BP tables based on height percentiles of P50 and P75 have far fewer screening thresholds(includes 88 thresholds)than the Industry Standard of more than 700,with high PPVs(about 80%to 90%),and NPV is high(about 98%)at the same time.Those simplified BP tables can be used in school health and child health to work for early and simple screening of children's hypertension.