Background: The prevalence of obesity, based on body mass index (BMI), among Chinese children and adolescents has increased for decades, but the relationship between trends in blood pressure (BP) and increasing BMI has not been studied.
Methods: BMI and BP measurements of 391,982 children aged 7-17 years were obtained from surveys in 2005 and 2010. The mean change and 95% confidence intervals (CIs) of BP were calculated, and the association between BMI and BP was assessed by using analysis of covariance and direct adjustment with the BMI distribution of 2005 survey.
Results: The mean systolic BP (SBP) and diastolic BP (DBP) increased 1.5 mm Hg (95% CI = 1.4-1.7 mm Hg) and 1.1 mm Hg (95%CI = 1.1-1.2 mm Hg) for boys and 1.2 mm Hg (95% CI = 1.1-1.3 mm Hg) and 1.0 mm Hg (95% CI = 1.0-1.1 mm Hg) for girls from 2005 to 2010, respectively. After adjustment for BMI, SBP and DBP in 2010 were 0.8mm Hg (95% CI = 0.8-0.9mm Hg) and 0.8mm Hg (95% CI = 0.7-0.8mm Hg) higher than in 2005, respectively (all P < 0.01). With adjustment for difference in BMI distribution in 2005 and 2010, the mean increase of SBP decreased by 40.5% and that of DBP by 26.9%.
Conclusions: BP among Chinese children and adolescents was on the rise from 2005 to 2010, which was consistent with the hypothesis that the rise in BP was in part attributable to the rise in BMI.
Keywords: BMI; adolescents; blood pressure; children; hypertension; trend..