Marco Giussani

Results of blood pressure screening in a population of school-aged children in the province of Milan: role of overweight.

Objectives To study the prevalence of high blood pressure (BP) in an Italian paediatric population, and to verify whether in this population elevated BP values are associated with overweight (OW). Study design Children (1206 males, 1210 females) from the lower-grade public schools (ages 6–11 years) were studied. Body weight, height and BP were measured in each child. Elevated BP was defined if resting systolic and/or diastolic BP values equalled or exceeded the 95th percentile according to gender, age and height, based on the US normative BP tables. Overweight children were identified using four different methods: (1) the classification based on the relative body weight; (2) the French references by Rolland-Cachera et al. (Am J Clin Nutr 1982; 36:178–184); (3) the International Obesity Task Force charts; and (4) the Italian charts defined by Cacciari et al. (Eur J Clin Nutr 2002; 56:171–180). Results The prevalence of high BP in our population was 4.2% and was significantly higher in females (65/1210 = 5.4%) than in males (37/1206 = 3.1%), P = 0.005. The different methods used to define OW provide different estimates of OW prevalence (from 17.0 to 38.6%). The percentage of high BP subjects was significantly higher in OW than in normal-weight children regardless of the method used for the definition of the weight class (P < 0.0001), in both genders. In addition, for each age range, absolute systolic and diastolic BP values were higher in OW as compared to normal-weight children both in males and in females (P < 0.0001). Conclusions Our study indicates the importance of performing BP screenings in the paediatric population, and to promote interventions that may reduce the prevalence of OW in children.

Usefulness of waist circumference for the identification of childhood hypertension.

Objective To investigate the ability of BMI and waist circumference, single and combined, in identifying children who are at risk of hypertension and in influencing absolute blood pressure values. Methods The body weight, height, waist circumference and blood pressure of 4177 5–11-year-old school children [2005 (48%) girls] were collected. Elevated blood pressure was defined if either systolic or diastolic blood pressure values or both were more than the 95th percentile according to sex, age and height (US normative blood pressure tables). Overweight and obese children were defined according to International Obesity Task Force BMI cut-offs. Results The prevalence of hypertension was 4.1% and increased together with weight class: 1.4% (n = 42/3076) in normal weight, 7.1% (n = 59/827) in overweight and 25% (n = 69/274) in obese (P < 0.001). Only BMI and waist circumference showed a remarkable ability to discriminate hypertensive children (areas under receiver operating characteristic curves, 0.84 and 0.76, respectively). The multivariate analysis showed that z-scores for both BMI and waist circumference were significantly related to the risk of hypertension with odds ratios of 3.59 (95% confidence interval, 2.55, 5.06) and 1.20 (95% confidence interval, 1.04, 1.39), respectively, after adjusting for sex and age. When the weight class was included in the multivariate analysis, waist circumference retained its ability to identify hypertensive children only in the obese class (odds ratio, 1.44; 95% confidence interval, 1.21, 1.72; P < 0.01). When considering blood pressure as a continuous variable, both weight class and waist circumference showed a significant effect on systolic and diastolic blood pressure absolute values (P < 0.01). The effect of waist circumference on blood pressure values was maintained even when corrected for BMI. Conclusion High blood pressure is strongly associated with excess weight. Waist circumference improves the ability of BMI to identify hypertension in obese children. Waist circumference is related to absolute blood pressure values in all weight classes.

Serum uric acid and blood pressure in children at cardiovascular risk.

OBJECTIVES: Hyperuricemia has been shown to be a strong correlate of hypertension in children. However, the complex interaction between serum uric acid (UA), systemic blood pressure (BP), and possibly confounding factors has been elucidated only in part. METHODS: We evaluated office BP as well as clinical and biohumoral parameters in a cross-sectional cohort of 501 children (280 boys and 221 girls) aged between 6 and 18 years (mean = 10.8 years) consecutively referred for cardiovascular risk assessment. RESULTS: Overall, 156 (31.1%) were normotensive, 122 (24.4%) showed transient hypertension, 87 (17.4%) had prehypertension, and 136 (27.1%) had hypertension. Altogether 33.3% and 40.5% of the study group were overweight or obese, respectively. There was a trend toward greater weight and waist circumference and higher BMI, Homeostasis Model Assessment index, and UA levels as the BP categories rose. Moreover, the prevalence of pubertal children, obesity, and waist-to-height ratio above 0.50 progressively increased from lower to upper BP categories. After adjusting for puberty, gender, BMI (z-score), Homeostasis Model Assessment index, and renal function, UA was found to be directly related to systolic and diastolic BP values (P = .03). Using normotensive children for comparison, the risk of showing prehypertension or hypertension increased by at least 50% for each 1 mg/dL UA increase (P < .01), whereas it doubled for children in the top gender-specific UA quartile (P < .03). CONCLUSIONS: Increased UA levels showed an independent predictive power for the presence of higher BP levels among a cohort of children at relatively high cardiovascular risk.

Hypertension, Prehypertension, and Transient Elevated Blood Pressure in Children: Association With Weight Excess and Waist Circumference

BACKGROUND To assess the prevalence of hypertension (H), prehypertension (PH), and transient elevated blood pressure (TH) and their relationship with weight class and waist circumference (WC) in an unselected population of Northern Italian children. METHODS A cross-sectional study was conducted in 5,131 children (5-11 years). Weight class was defined according to the International Obesity Task Force references, H and PH according to the National High Blood Pressure Education Program. A child was classified as having PH or H when systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) at first screening were > or =90th percentile and the mean of three subsequent measures was between the 90th and 95th or > or =95th percentile, respectively. When BP values at the first screening were > or =90th percentile but the mean of three subsequent measures was <90th percentile the child was classified as having TH. RESULTS A proportion of 3.4% presented H, 2.7% PH, and 10.4% TH, 20% overweight, and 6% obesity. Weight class and WC were significantly associated to an increased risk of falling into any of the hypertensive categories. In children with TH BP z-scores of the mean of the three subsequent measurements following the first screening were significantly higher than BP z-scores observed in normotensive children (P value <0.001). CONCLUSIONS Weight class and WC are associated with BP. This is observed not only for H but also for PH, and for nonsustained forms of H. Prospective studies are needed to assess whether children with PH and TH will develop sustained H.

Analysis of Heart Period and Arterial Pressure Variability in Childhood Hypertension: Key Role of Baroreflex Impairment

In adults, initial stages of hypertension are associated with elevated sympathetic drive and significant alterations in indirect autonomic markers. There is growing evidence that children in the highest-pressure percentiles will be more likely to develop hypertension in adulthood, although mechanisms are not understood. We assessed whether computer analysis of RR interval and arterial blood pressure variability could detect early autonomic alterations in childhood hypertension, as assessed by noninvasive time and frequency domain measures of baroreflex regulation. We studied 75 children, subdivided in 3 subgroups of similar age (9.7±0.2 years): control subjects, prehypertensive children (ie, children with arterial pressure values >90th and <95th percentile for age, gender, and height), and children in the hypertensive range (ie, >95th percentile; systolic arterial pressure: 97±3/57±2, 121±5/70±1, and 128±2/80±2 mm Hg, respectively). We observed that hypertensive children demonstrate a significant impairment of the baroreflex as compared with control subjects (index α: 20±2 and 40±4 ms/mm Hg; spontaneous baroreflex slope: 20±2 and 37±5; ms/mm Hg; P <0.05 in both cases) and reduced RR variance. A similar baroreflex impairment is also observed in children whose arterial pressure falls short of this limit, ie, in the prehypertensive range. In conclusion, hypertensive children display a marked baroreflex impairment. A similar baroreflex impairment is also observed in the prehypertensive state. Baroreflex assessment could furnish additional information in the clinical assessment of pediatric hypertension.

Focus on prevention, diagnosis and treatment of hypertension in children and adolescents

The European Society of Hypertension has recently published its recommendations on prevention, diagnosis and treatment of high blood pressure in children and adolescents. Taking this contribution as a starting point the Study Group of Hypertension of the Italian Society of Pediatrics together with the Italian Society of Hypertension has conducted a reappraisal of the most recent literature on this subject. The present review does not claim to be an exhaustive description of hypertension in the pediatric population but intends to provide Pediatricians with practical and updated indications in order to guide them in this often unappreciated problem.This document pays particular attention to the primary hypertension which represents a growing problem in children and adolescents. Subjects at elevated risk of hypertension are those overweight, with low birth weight and presenting a family history of hypertension. However, also children who do not present these risk factors may have elevated blood pressure levels. In pediatric age diagnosis of hypertension or high normal blood pressure is made with repeated office blood pressure measurements that show values exceeding the reference values. Blood pressure should be monitored at least once a year with adequate methods and instrumentation and the observed values have to be interpreted according to the most updated nomograms that are adjusted for children’s gender, age and height. Currently other available methods such as ambulatory blood pressure monitoring and home blood pressure measurement are not yet adequately validated for use as diagnostic instruments. To diagnose primary hypertension it is necessary to exclude secondary forms. The probability of facing a secondary form of hypertension is inversely proportional to the child’s age and directly proportional to blood pressure levels. Medical history, clinical data and blood tests may guide the differential diagnosis of primary versus secondary forms. The prevention of high blood pressure is based on correct lifestyle and nutrition, starting from childhood age. The treatment of primary hypertension in children is almost exclusively dietary/behavioral and includes: a) reduction of overweight whenever present b) reduction of dietary sodium intake c) increase in physical activity. Pharmacological therapy will be needed rarely and only in specific cases.

Effects of exposure to high altitude on plasma endothelin-1 levels in normal subjects

Objective: To assess whether the hypoxia associated with exposure to high altitude affects plasma endothelin-1 levels, and whether changes in endothelin-1 are related to those in systemic and pulmonary blood pressure. Design: Eight normal subjects ascended Mount Everest to an altitude of 5050 m within a period of 8 days (study 1) and 10 ascended Mount Rosa in the Italian Alps to an altitude of 4559 m within 2 days (study 2). In study 1 systemic blood pressure, heart rate, haematocrit, haemoglobin oxygen saturation (evaluated by percutaneous oximetry) and venous plasma endothelin-1 were measured several times during the ascent, and twice more during the time spent at high altitude. In study 2 the same parameters as well as systolic pulmonary pressure by echocardiography were evaluated on the second day of resting at 4559 m. In both studies, data obtained during the expeditions were compared with those collected from the same subjects at sea level. Results: In study 1 plasma endothelin-1 increased progressively up to 4240 m (from 1.8±0.1 pg/ml at sea level to 2.7±0.2pg/ml) and decreased slightly thereafter; these increments were directly related to the decrements in percutaneous oxygen saturation, which, at that altitude, fell from 98.6±0.2% at sea level to 80.8±0.4%. Blood pressure and haematocrit also rose in response to exposure to high altitude but these changes were not related to changes in endothelin-1. In study 2 the increments in plasma endothelin-1 were similar to those observed in study 1 and the changes again correlated with changes in oxygen saturation as well as with those in systolic pulmonary pressure. On average, systolic pulmonary pressure increased from 19 ± 1 to 26±1.9mmHg, whereas systemic blood pressure and haematocrit were unchanged. Conclusion: Exposure to high altitude is associated with consistent increases in plasma endothelin-1. This is probably the result of augmented secretion of the peptide in response to hypoxia and may contribute to the physiological adaptation of the pulmonary circulation to this condition.

Superiority of acceleration and acceleration time over pulsatility and resistance indices as screening tests for renal artery stenosis

Objective To compare the accuracy of four echo-Doppler-derived velocimetric indices (pulsatility and resistance indices, acceleration and acceleration time) in detecting renal artery stenosis in hypertensive patients. Patients and methods In 73 hospitalized patients with moderate-to-severe hypertension, 18 of whom had normal renal arteries and 55 renal artery stenosis (50-95%) either atherosclerotic (30 cases, five bilateral) or fibromuscular dysplasia (25 cases, two bilateral), we measured the four velocimetric indices using the lateral abdominal approach and sampling Doppler waveforms distally to the stenosis. The diagnostic accuracy of each index was calculated using as cut-off limit the ideal threshold determined with the receiver-operating characteristic curves. Results On average all of the indices were altered significantly in arteries with stenosis of both aetiologies with respect to normal arteries, the alterations of pulsatility and resistance indices being, however, less pronounced than those of acceleration and acceleration time, particularly in atherosclerotic stenosis. With the cut-off limits of 0.93, 0.59 and 7.4 m/s2 and 60 ms, respectively, for pulsatility and resistance indices, acceleration and acceleration time, their diagnostic accuracies were 80, 73, 93 and 92%. In stenotic arteries, only the acceleration time was correlated with the degree of arterial narrowing, whereas, in normal arteries, only pulsatility and resistance indices were directly correlated with the age of patients. Conclusions Acceleration and acceleration time are more accurate indices than pulsatility and resistance to screen for renal artery stenosis, probably because their alterations are less attenuated by the counterbalancing effects of age and of atherosclerosis.

Cardiovascular risk assessment in children: role of physical activity, family history and parental smoking on BMI and blood pressure

Objective: Aim of the study was to assess the role of family history, physical activity and parental smoking in the prediction of BMI, SBP and hypertension risk in children. Participants and methods: In a paediatric primary care setting, a sample of 1310 children aged 5–14 years was systematically selected by 48 family paediatricians in northern Italy. BMI, waist circumference-to-height ratio (WtHr), SBP and DBP were measured and the information on the presence of small birth weight for gestational age (SGA) and early adiposity rebound (EAR) was collected. Data concerning exercise, video time, family history for cardiovascular diseases and parental smoking were derived from parental interview. Data were collected using an ’ad hoc designed’ electronic sheet available online. Results: Multiple linear regression showed that the presence of EAR, low exercise (<2 h/week), high video time (>2 h/day TV/videogames/computer) and parental smoking were associated to higher BMI (z-score; P < 0.005). Age, BMI (z-score), WtHr, presence of SGA, low exercise, high video time and family history of cardiovascular diseases were associated to SBP values (P < 0.03). Logistic regression analysis showed that factors related to risk of hypertension and prehypertension were BMI (z-score; odds ratio, OR 2.63; 95% confidence interval, CI 2.12–3.28), WtHr (OR 1.13; 95% CI 1.10–3.28) and low exercise (OR 1.58; 95% CI 1.12–2.24; P <0.01). Conclusion: Our study demonstrates that a simple tool like a cardiovascular multi-item sheet can provide useful information to paediatricians for child health. Physical exercise plays a pivotal role in obesity prevention and protection from hypertension risk.

Adiponectin and hypertension in normal-weight and obese children

BACKGROUND Adiponectin (AD) reduces the risk of hypertension because of its anti-inflammatory, antiatherogenic, and insulin-sensitizing properties. The study described here was done to evaluate the interrelationships of AD, blood pressure (BP), obesity, body-fat distribution, puberty, and insulin resistance in a selected group of children. METHODS The study was a cross-sectional, observational study of 186 children ranging in age from 5-18 years and grouped according to weight class (obese (OB), n = 100; normal weight (NW), n = 86) and BP category (hypertensive (HT) n = 79; normotensive (NT); n = 107). The children were also classified on the basis of fat distribution (waist circumference/height ratio). Their blood glucose, insulin, and AD concentrations were assayed, and their homeostatic model assessment (HOMA) index was calculated as an estimate of insulin resistance. RESULTS Serum AD was lower in OB-HT (7,111±4,163ng/ml) than in NW-NT (12,622±6,276ng/ml) children (P < 0.0001). Intermediate values of AD were found in OB-NT (9,099±3,988ng/ml) and NW-HT (9,808±4,211ng/ml) children. Weight and waist circumference-to-height ratio, BP category, and pubertal stage were all independently and inversely associated with serum levels of AD (P < 0.02). In a logistic regression model, after adjustment for body mass index (BMI) and waist circumference/height ratio, serum levels of AD maintained an independent association with hypertension (P < 0.05), as did also the HOMA index (P < 0.05). A reduction of 10 times (i.e., one unit on the log(10) scale) in AD serum levels was associated with a 50% increased probability of having hypertension. CONCLUSIONS In childhood, serum levels of AD are inversely related to hypertension. This relationship is partly independent of obesity, fat distribution, and insulin resistance. Low values of AD in both OB and NW children are associated with a higher probability of hypertension.