Trends in Adolescents Obesity and the Association between BMI and Blood Pressure: A Cross-Sectional Study in 714,922 Healthy Teenagers

BACKGROUND Seventeen percent of youth in the United States are obese. Obesity has been linked to higher prevalence of hypertension. Past studies were limited by their size and conflicting results. The aim of this study was to analyze trends in adolescents' obesity between 1998 and 2011 and to evaluate the relationship between blood pressure and body mass index (BMI) in healthy adolescents. METHODS All adolescents who underwent a medical exam in the years 1998-2011 and were found fit for combat duties in the Israeli Defense Force were included. RESULTS The cohort included 714,922 healthy adolescents with 59% of them being males. The mean age was 17.4 +/- 0.45 and mean BMI was 22 +/- 3.5 kg/m(2). The percentage of overweight adolescents (BMI > 25 kg/m(2)) has increased from 13.2% in 1998 to 21% in 2011, P < 0.001. The mean systolic and diastolic blood pressures increased with increasing BMI deciles (systolic blood pressure by 10 mm Hg and diastolic blood pressure by 3-4 mm Hg from the 1st decile to the 10th decile, P < 0.001 for both). In multivariate analysis, each increase of 1 unit of BMI was associated with an increased risk of systolic blood pressure above 130 mm Hg in both males (OR = 1.108, 95% CI 1.107-1.110, P < 0.001) and females (OR = 1.114, 95% CI 1.139-1.146, P < 0.001). CONCLUSIONS BMI in adolescents is significantly associated with systolic blood pressure and diastolic blood pressure in both genders and in both the normal weight and overweight groups. There has been consistent trend of increasing BMI values over recent years.