Body mass index percentiles and elevated blood pressure among children and adolescents.

It is well established that obesity is associated with an increased risk of elevated and high blood pressure (BP) in children and adolescents. However, it is uncertain whether there is an increase in the risk of elevated and high BP associated with an increase of body mass index (BMI) among children and adolescents whose BMI is in the accepted normal range. Data were available for 58 899 children and adolescents aged 6-17 years from seven national cross-sectional surveys in China, India, Iran, Korea, Poland, Tunisia, and the United States. The subjects were divided into eight percentile subgroups according to their BMI levels based on the World Health Organization recommendations. Elevated BP and high BP were defined using the 2016 international child BP criteria. Compared with the reference subgroup of the 5th-24th percentiles, the odds ratios (ORs) for high BP were 1.27 (95% confidence interval [CI], 1.14-1.41; P < 0.001) in the 25th-49th percentile subgroup, 1.55 (95% CI, 1.39-1.73; P < 0.001) in the 50th-74th percentile subgroup, and 2.17 (95% CI, 1.92-2.46; P < 0.001) in the 75th-84th percentile subgroup, respectively, after adjustment for sex, age, race/ethnicity, height and country. Additionally, the corresponding ORs for elevated BP were 1.21 (95% CI, 1.10-1.32; P < 0.001), 1.55 (95% CI, 1.42-1.69; P < 0.001), and 1.80 (95% CI, 1.62-2.01; P < 0.001), respectively. In conclusion, a BMI in the 25th-84th percentiles, within the accepted normal weight range, was associated with an increased risk of elevated and high BP among children and adolescents. It is important for children and adolescents to keep a BMI at a low level in order to prevent and control hypertension.

International Waist Circumference Percentile Cutoffs for Central Obesity in Children and Adolescents Aged 6 to 18 Years.

CONTEXT: No universal waist circumference (WC) percentile cutoffs used have been proposed for screening central obesity in children and adolescents. OBJECTIVE: To develop international WC percentile cutoffs for children and adolescents with normal weight based on data from 8 countries in different global regions and to examine the relation with cardiovascular risk. DESIGN AND SETTING: We used pooled data on WC in 113,453 children and adolescents (males 50.2%) aged 4 to 20 years from 8 countries in different regions (Bulgaria, China, Iran, Korea, Malaysia, Poland, Seychelles, and Switzerland). We calculated WC percentile cutoffs in samples including or excluding children with obesity, overweight, or underweight. WC percentiles were generated using the general additive model for location, scale, and shape (GAMLSS). We also estimated the predictive power of the WC 90th percentile cutoffs to predict cardiovascular risk using receiver operator characteristics curve analysis based on data from 3 countries that had available data (China, Iran, and Korea). We also examined which WC percentiles linked with WC cutoffs for central obesity in adults (at age of 18 years). MAIN OUTCOME MEASURE: WC measured based on recommendation by the World Health Organization. RESULTS: We validated the performance of the age- and sex-specific 90th percentile WC cutoffs calculated in children and adolescents (6-18 years of age) with normal weight (excluding youth with obesity, overweight, or underweight) by linking the percentile with cardiovascular risk (area under the curve [AUC]: 0.69 for boys; 0.63 for girls). In addition, WC percentile among normal weight children linked relatively well with established WC cutoffs for central obesity in adults (eg, AUC in US adolescents: 0.71 for boys; 0.68 for girls). CONCLUSION: The international WC cutoffs developed in this study could be useful to screen central obesity in children and adolescents aged 6 to 18 years and allow direct comparison of WC distributions between populations and over time.

Impact of the 2017 American Academy of Pediatrics Guideline on Hypertension Prevalence Compared With the Fourth Report in an International Cohort.

In 2017, the American Academy of Pediatrics (AAP) updated the clinical practice guideline for high blood pressure (BP) in the pediatric population. In this study, we compared the difference in prevalence of elevated and hypertensive BP values defined by the 2017 AAP guideline and the 2004 Fourth Report and estimated the cardiovascular risk associated with the reclassification of BP status defined by the AAP guideline. A total of 47 200 children and adolescents aged 6 to 17 years from 6 countries (China, India, Iran, Korea, Poland, and Tunisia) were included in this study. Elevated BP and hypertension were defined according to 2 guidelines. In addition, 1606 children from China, Iran, and Korea who were reclassified upward by the AAP guideline compared with the Fourth Report and for whom laboratory data were available were 1:1 matched with children from the same countries who were normotensive by both guidelines. Compared with the Fourth Report, the prevalence of elevated BP defined by the AAP guideline was lower (14.9% versus 8.6%), whereas the prevalence of stages 1 and 2 hypertension was higher (stage 1, 6.6% versus 14.5%; stage 2, 0.4% versus 1.7%). Additionally, comparison of laboratory data in the case-control study showed that children who were reclassified upward were more likely to have adverse lipid profiles and high fasting blood glucose compared with normotensive children. In conclusion, the prevalence of elevated BP and hypertension varied significantly between both guidelines. Applying the new AAP guideline could identify more children with hypertension who are at increased cardiovascular risk.

Height-specific blood pressure cutoffs for screening elevated and high blood pressure in children and adolescents: an International Study.

Pediatric blood pressure (BP) reference tables are generally based on sex, age, and height and tend to be cumbersome to use in routine clinical practice. In this study, we aimed to develop a new, height-specific simple BP table according to the international child BP reference table based on sex, age and height and to evaluate its performance using international data. We validated the simple table in a derivation cohort that included 58,899 children and adolescents aged 6-17 years from surveys in 7 countries (China, India, Iran, Korea, Poland, Tunisia, and the United States) and in a validation cohort that included 70,072 participants from three other surveys (China, Poland and Seychelles). The BP cutoff values for the simple table were calculated for eight height categories for both the 90th ("elevated BP") and 95th ("high BP") percentiles of BP. The simple table had a high performance to predict high BP compared to the reference table, with high values (boys/girls) of area under the curve (0.94/0.91), sensitivity (88.5%/82.9%), specificity (99.3%/99.7%), positive predictive values (93.9%/97.3%), and negative predictive values (98.5%/97.8%) in the pooled data from 10 studies. The simple table performed similarly well for predicting elevated BP. A simple table based on height only predicts elevated BP and high BP in children and adolescents nearly as well as the international table based on sex, age, and height. This has important implications for simplifying the detection of pediatric high BP in clinical practice.

Performance of Eleven Simplified Methods for the Identification of Elevated Blood Pressure in Children and Adolescents.

The identification of elevated blood pressure (BP) in children and adolescents relies on complex percentile tables. The present study compares the performance of 11 simplified methods for assessing elevated or high BP in children and adolescents using individual-level data from 7 countries. Data on BP were available for a total of 58 899 children and adolescents aged 6 to 17 years from 7 national surveys in China, India, Iran, Korea, Poland, Tunisia, and the United States. Performance of the simplified methods for screening elevated or high BP was assessed with receiver operating characteristic curve (area under the curve), sensitivity, specificity, positive predictive value, and negative predictive value. When pooling individual data from the 7 countries, all 11 simplified methods performed well in screening high BP, with high area under the curve values (0.84-0.98), high sensitivity (0.69-1.00), high specificity (0.87-1.00), and high negative predictive values (≥0.98). However, positive predictive value was low for most simplified methods, but reached ≈0.90 for each of the 3 methods, including sex- and age-specific BP references (at the 95th percentile of height), the formula for BP references (at the 95th percentile of height), and the simplified method relying on a child's absolute height. These findings were found independently of sex, age, and geographical location. Similar results were found for simplified methods for screening elevated BP. In conclusion, all 11 simplified methods performed well for identifying high or elevated BP in children and adolescents, but 3 methods performed best and may be most useful for screening purposes.

Establishing International Blood Pressure References Among Nonoverweight Children and Adolescents Aged 6 to 17 Years.

BACKGROUND: Several distributions of country-specific blood pressure (BP) percentiles by sex, age, and height for children and adolescents have been established worldwide. However, there are no globally unified BP references for defining elevated BP in children and adolescents, which limits international comparisons of the prevalence of pediatric elevated BP. We aimed to establish international BP references for children and adolescents by using 7 nationally representative data sets (China, India, Iran, Korea, Poland, Tunisia, and the United States). METHODS AND RESULTS: Data on BP for 52 636 nonoverweight children and adolescents aged 6 to 19 years were obtained from 7 large nationally representative cross-sectional surveys in China, India, Iran, Korea, Poland, Tunisia, and the United States. BP values were obtained with certified mercury sphygmomanometers in all 7 countries by using standard procedures for BP measurement. Smoothed BP percentiles (50th, 90th, 95th, and 99th) by age and height were estimated by using the Generalized Additive Model for Location Scale and Shape model. BP values were similar between males and females until the age of 13 years and were higher in males than females thereafter. In comparison with the BP levels of the 90th and 95th percentiles of the US Fourth Report at median height, systolic BP of the corresponding percentiles of these international references was lower, whereas diastolic BP was similar. CONCLUSIONS: These international BP references will be a useful tool for international comparison of the prevalence of elevated BP in children and adolescents and may help to identify hypertensive youths in diverse populations.

Waist Circumference and Waist-to-Height Ratio Distributions in Polish and German Schoolchildren: Comparative Analysis.

BACKGROUND: To analyze differences in the distributions of waist circumference (WC) and waist-to-height ratio (WHtR) between Polish (PL) and German (GE) children and adolescents. METHODS: Two samples of children and adolescents aged 7-18 y: From PL (n = 11,326) GE (n = 8,218) participated. The two WC cut-off points (WC1 as central fat distribution and WC2 as central obesity) corresponding at age 18 to the adult criteria were determined. Furthermore, the mean WC cut-off points (WC1m, WC2m) for boys and girls aged 14-18 from both countries were evaluated. For the WHtR, values over 0.5 were used as a definition of central fat distribution. The effect of different WC and WHtR criteria on the prevalence of abdominal obesity in both study groups was evaluated. RESULTS: The mean and percentile values of WC and WHtR were generally higher in all German children as compared to their peers from Poland. When WC1m is used, the mean (95% CI) prevalence of central fat distribution in the 14-18 y Polish groups was lower (P < 0.05) than those from Germany (boys: 4.4% (3.6-5.2) vs. 8.9% (7.3-10.5); girls: 10.7% (9.0-12.3) vs. 26.4% (23.2-29.6)), whereas, using the WHtR > 0.5, the results were similar for boys - 6.7% (5.9-7.5) vs. 8.5% (8.1-8.9); they were significantly (P < 0.05) lower for Polish and German girls: 5.3% (5.0-5.6) vs. 12.7% (9.7-16.4). The prevalence of central obesity using WC2m as a criterion in the Polish vs. German groups was as follows: (boys - 1.1% (0.8-1.4) vs. 3.1% (2.2-4.0), P < 0.05; girls - 3.1% (2.5-3.7) vs. 10.2% (8.4-12.0), P < 0.05). CONCLUSIONS: The results highlight the greater central obesity associated with the German children, both in terms of WC and WHtR, in comparison to their peers from Poland. The prevalence of AO is significantly associated with the criteria used. The results demonstrate the need for the development of international WC references for pediatric subjects.

Blood pressure references for Polish children and adolescents.

The objective of this study was to develop age- and gender-specific reference ranges for blood pressure in a large national database on blood pressure levels throughout childhood and adolescence in young Poles. A prospective cross-sectional study was performed in 2002-2005 in the representative sampling sites, selected randomly from the entire Poland. Altogether, 6,447 school pupils, aged 7-18 years, were involved in the study of which 3,176 were boys and 3,271 were girls. Statistical analysis was performed using STATISTICA for Windows 7.1. The normal range of blood pressure, determined by age and the category of body height percentiles, revealed percentiles values which might serve as reference values to identify cases of high normal blood pressure (the mean blood pressure between 90th and 95th percentiles for age and gender) and hypertension (the mean blood pressure equals or exceeds the 95th percentiles on at least three occasions).

Prevalence of excessive body weight and high blood pressure in children and adolescents in the city of Lódz.

BACKGROUND: Overweight and elevated blood pressure in children and adolescents are two independent risk factors of basic importance for early prevention of cardiovascular and metabolic diseases. AIM: To evaluate the prevalence of overweight and elevated blood pressure in children and adolescents aged 7-18 years from the city of Lódz. METHODS: A total of 25,309 children and adolescents (12,669 girls and 12,640 boys) aged 7-19 years from 111 schools in the city of Lódz were examined. Basic anthropometric measurements (body mass and height) as well as three independent blood pressure measurements using the auscultatory method were performed. The prevalence of overweight and obesity were evaluated based on BMI analysis and using international criteria (IOTF). The prevalence of prehypertension state and hypertension was evaluated using the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. RESULTS: The mean prevalence of overweight (without obesity) was 15.1% (13.2% for girls and 17% for boys) and obesity was found in 3.7% of children (2.9% of girls and 4.4% of boys). Prevalence of the prehypertensive state and hypertension was 11.1% and 4.9%, respectively. In the younger groups of children aged 7-13 years the prevalence of overweight as well as elevated blood pressure was significantly (p <0.001) higher than in groups aged 14-19 years. CONCLUSIONS: The results indicate that the prevalence of overweight as well as elevated blood pressure is significantly higher in younger groups of children. The observed relations may result from specific social determinants and improper nutritional habits. The results show that intensive preventive activities should also be directed towards younger groups of children.

[Antioxidative defense and level of microelements in youth with hypertension]. / Status antyoksydacyjny a stezenie pierwiastków sladowych u mlodziezy z podwyzszonym cisnieniem tetniczym.

UNLABELLED: In recent years we observed increased interest of free radical processes accompanying varying physiological and pathological reactions. THE AIM OF THIS STUDY was an evaluation some of serum microelements (zinc, manganium, chromium, selenium) in serum and antioxidative defense in youth with hypertension. MATERIAL AND METHODS: The group of 88 youth aged 9-18 with normal blood pressure, prehypertension and hypertension was examined. Blood was taken to examine microelements content and antioxidative barrier activity. Microelements content was estimated with the method ICP-AES. Superoxide dismuthase activity in red blood cells was estimate with the method by Misra and Fridovich, glutatione peroxidase activity with the method by Sedlak and Lindsay in modification by Little and O'Brien and catalase activity with the method of Beers and Sizer. RESULTS: In subgroup with higher blood pressure we observed decreased tendency in enzymatic antioxidant activity (Cat, GSA-Px, SOD) in red blood cells and lowering levels of vitamins C and E in comparison to persons with normal blood pressure. Concentrations of estimated microelements drowed decreased levels in persons with hypertension. CONCLUSIONS: Results of our study suggest that disturbance in pro - and anti-oxidative balance observed in youth with first state of hypertension may play an important role in pathogenesis of hypertension.

[Body mass index in the school age children and youth from the city of Lodz]. / Wskaznik masy ciala u dzieci i mlodziezy lódzkiej w wieku szkolnym.

UNLABELLED: Excessive body mass in children and youth constitutes each year a more increasing problem in our country. Early diagnosis based on current appropriate norms and recommendations of main pediatric and scientific societies appears to be of great importance. THE AIM OF THE STUDY: Percentile distribution of body mass index (BMI) for children and adolescents (aged 7-19 years) dwelling in Lodz were constructed and compared with the norms included in the International Obesity Task Force (IOTF) project. MATERIAL AND METHODS: A total of 26,542 children and adolescents (13,358 girls and 13,184 boys) participated in the study. Measurements of basic anthropometric parameters were performed and BMI determined in all the subjects. The LMS method was used to construct the BMI percentile distributions. Sex dimorphism of the BMI as well as the differences between the border values of BMI distribution for children from Lodz and the IOTF norms were analysed. RESULTS: The children from Lodz, particularly girls, reveal significantly lower BMI values defining obesity (c95) as compared to the IOTF norms. The maximal difference concerned 18-year-old girls and was 2.62 kg/m2 (9.1%). BMI values indicating overweight in the Lodz children (c85) were more similar to the international norms of IOTF (maximal difference around 5%). CONCLUSIONS: The results confirm justifiability of using a local norm as a criterion for evaluation of obesity at the developmental age. Application of the IOTF norms in the assessment of obesity prevalence in children and youth in Poland may be associated with a considerable underestimation of this problem.

[Bronchial asthma prevalence in children and youth with overweight]. / Czestosc wystepowania astmy oskrzelowej u dzieci i mlodziezy z nadmierna masa ciala.

THE AIM OF THE STUDY: Relationships between bronchial asthma prevalence in children and youth and selected nutritional indices together with fatty tissue distribution were analyzed. MATERIAL AND METHODS: The study comprised randomly chosen group of 126 children and youth living in the city of Lodz, between the ages from 9 to 17 years (74 boys, 52 girls) including 25 subjects with mild and 34 with moderate asthma. In all participants basic anthropometric and percentage evaluation of the fat content (FAT%) by means of a bioimpedance method were performed. A level of 85 centiles of the body mass index (BMI) determined on the basis of centile charts was regarded as a criterion for overweight. Fatty tissue distribution was assessed basing on the waist-to-hip ratio (WHR). RESULTS: In girls with overweight or obesity (BMI > 85%) a statistically significant prevalence of asthma (71.4%; p < 0.01) with different intensity was observed, as compared to girls with a normal BMI (23.7%). Similar tendencies related to the WHR index and the total fat content (FAT%) were also notified. Asthma was found to occur more frequently in the group of girls with overweight or obesity as well as with abnormal (abdominal) distribution of fatty tissue. CONCLUSIONS: Results reveal significant relations between overweight and abnormal distribution of fatty tissue and asthma prevalence in girls. Such relationships did not appear in the group of boys. Obese children with bronchial asthma--mainly girls--more frequently require a careful approach towards the pharmacological control of asthma due to obesity-related complications e.g. hypertension.

[The heart rate variability analysis in youth and children with bronchial asthma]. / Analiza wybranych parametrów zmiennosci rytmu serca u mlodziezy i dzieci chorych na astme oskrzelowa.

UNLABELLED: The aim of the study was analysis of the spectral parameters of heart rate variability (HRV) in children and youth with different intensity of bronchial asthma. MATERIAL AND METHODS: The study was conducted in the group of 107 children and adolescents, aged 10-17 years, comprising 58 healthy subjects and 49 with bronchial asthma (22 with mild and 27 with moderate asthma). Spectral HRV parameters at rest and under active orthostatic test conditions (5 min--supine position, 5 min--standing position) were analysed in two age subgroups: group A--children aged 10-13 years and group B--youth aged 14-17 years. RESULTS: In both subgroups at rest a growing tendency for high frequency components (HF) of HRV spectra was observed together with greater intensity of asthma. In the youth group with moderate asthma, the HF component (40.8 +/- 14.0 n.u.) at rest was significantly higher (p < 0.05) than in the age-matched control (30.8 +/- 10.7 n.u.). In all the groups examined assuming erect position resulted in a significant rise in LF/HF index, which was most pronounced in the groups with mild (p < 0.01) and moderate asthma (p < 0.05). CONCLUSIONS: The study confirmed a significant association between the vagal activity in children and youth and frequency and intensity of bronchial asthma. A short-term HRV analysis can be utilised in the assessment of autonomic mechanism role in the development of bronchial asthma in children and youth.