Last update:
24-May-2014

OBJECTIVE To examine the factors which affect the cardiovascular function of overweight/obese pre-pubertal children and adolescents.

METHOD A total of 1,397 healthy children aged 9−14 years participated in the study. The subjects were divided according to their gender (boys: n=728, girls: n=699), age (9−10 years: n=499, 11−12 years: n=408, 13−14 years: n=490), arterial blood pressure (BP) (normotensive: n=1,169, pre-hypertensive: n=101, level I hypertension: n=96, level II hypertension: n=31) and weight (normal-weight: n=984, overweigh: n=280, obese: n=133). Measurements were made of the anthropometric characteristics (height, body mass), arterial BP (systolic, diastolic) and resting heart rate (Hr) in order to determine the pulse pressure, mean arterial BP, double product, stroke volume, cardiac output, peripheral resistance and cardiac index.

RESULTS In this sample, 70.4% were of normal weight and the prevalence of overweight and obesity was 20.1% and 9.5%, respectively. The prevalence of elevated BP was 11.5% in the overweight/obese boys and 9.1% in the overweight/obese girls. The odds ratio (OR) and the relative risk (RR) of both obesity and hypertension were OR=7.36 (95% CI: 4.82–11.24) and RR=4.91 (95% CI: 3.49–6.91) for boys and OR=4.29 (95% CI: 2.79–6.61) and RR=3.27 (95% CI: 2.31–4.63) for girls. The normotensive normal-weight children, irrespective of gender, presented more favourable values of heart rate, double product and cardiac index than the hypertensive overweight/obese children (p<0.001). Stepwise multiple regression using the cardiac index as the dependent variable (y=5.312−0.049*W+0.053*Hr−0.076*DP+0.036*SP−0.175*age), showed that 92.5% of the total variance was explained by body mass (W: 53%), Hr (Hr: 14.3%), diastolic BP (DP: 14.1%), systolic BP (SP: 8.5%) and age (age: 2.6%). In addition, negative correlation was demonstrated between the body mass index (BMI) and the cardiac index (r=-0.646, p<0.001) and positive correlation between BMI and the other hemodynamic parameters (r=0.211 to 0.517, p<0.01).

CONCLUSIONS Increased body mass and age affect the cardiac function of overweight/obese prepubertal children and adolescents, irrespective of gender, and are associated with an increased risk of development of hypertension, in comparison with normal weight peers. In clinical practice, it is necessary to implement prognostic indicators in childhood and adolescence aimed at the early detection of risk factors for cardiovascular disease in adulthood.

Key words: Blood pressure, BMI, Obesity, Risk factors, Schoolchildren.