The association between obesity and blood pressure in Thai public school children.

BACKGROUND: The prevalence of obesity has substantially increased in the past 3 decades in both developed and developing countries and may lead to an increase in high blood pressure (BP) at an early age. This study aimed to determine the prevalence of obesity and its association with blood pressure among primary school children in central Thailand.

METHODS: A cross-sectional study was conducted in two public schools in Bangkok in 2012. A total of 693 students (317 boys and 376 girls) aged 8-12 years participated voluntarily. Anthropometric measurements of weight, height, waist circumference (WC) and BP were collected. Fasting venous blood samples were obtained for biochemical analysis of fasting plasma glucose (FPG) and lipid parameters. Child nutritional status was defined by body mass index (BMI) for age based on the 2000 Center for Diseases Control and Prevention growth charts. The cutoff for abdominal obesity was WC at the 75 percentile or greater. Hypertension was defined according to the 2004 Pediatrics US blood pressure reference. Multinomial logistic regression was used to examine the relationship between high BP and obesity after controlling for other covariates.

RESULTS: The prevalence of obese children was 30.6% for boys and 12.8% for girls (mean prevalence 20.9%). Pre-hypertension (Pre-HT) was 5.7% and 2.7% for boys and girls and hypertension (HT) was 4.7% for boys and 3.2% for girls, respectively. Children with pre-HT and HT had significantly higher body weight, height, WC, BMI, SBP, DBP, TG, and TC/HDL-C levels but lower HDL-C levels than those children with normotension. After controlling for age, sex, glucose and lipid parameters, child obesity was significantly associated with pre-HT and HT (odds rations (ORs) = 9.00, 95% CI: 3.20-25.31 for pre-HT and ORs = 10.60, 95% CI: 3.75-30.00 for HT). So also was WC (abdominal obesity) when considered alone (ORs = 6.20, 95% CI: 2.60-14.81 for pre-HT and ORs = 13.73, 95% CI: 4.85-38.83 for HT) (p-value < 0.001).

CONCLUSIONS: Obesity among school children was positively associated with higher BP. Prevention of childhood obesity should be strengthened to prevent the risk of early high BP including cardiovascular risk factors.