Blood pressure effects of adiposity in non-overweight children aged 6-17 years.

Background: Obesity is a well-established risk factor of elevated blood pressure; however, the relationships between normal weight status and the risk of hypertension and pre-hypertension are not clear.

Aim: The aim of this study is to describe the blood pressure effects of adiposity in non-overweight children.

Methods And Results: In total, 588 097 non-overweight children aged 6-17 years were included from the National Surveys on Students' Constitution and Health. A non-linear relationship was found between age- and gender-standardised body mass index (BMI) z-score and pre-hypertension and hypertension, respectively. The odds ratios and 95% confidence intervals [ORs (95% CIs)] of pre-hypertension were 0.61 (0.59-0.63), 0.67 (0.65-0.68), 0.83 (0.83-0.84), 1.00 (reference), 1.13 (1.12-1.14), 1.18 (1.16-1.20) and 1.20 (1.18-1.22) for BMI z-scores of -1.2, -1.0, -0.5, 0 (reference), 0.5, 0.7 and 0.8, respectively. The ORs (95% CIs) of hypertension were 0.56 (0.54-0.58), 0.62 (0.61-0.64), 0.81 (0.80-0.82), 1.00 (reference), 1.17 (1.16-1.18), 1.23 (1.22-1.5) and 1.27 (1.24-1.29) for BMI z-scores of -1.2, -1.0, -0.5, 0 (reference), 0.5, 0.7 and 0.8, respectively. The above-mentioned associations were consistent in sub-group analysis by age, gender and height.

Conclusions: Non-linear relationships of BMI z-scores with pre-hypertension and hypertension were found in non-overweight children. Interventions to control blood pressure are also important in non-overweight children.