Prevalence of hypertension in overweight and obese children from a large school-based population in Shanghai, China

Background: The ongoing rise in the prevalence of hypertension in children and adolescents is considered to be accompanied with the epidemic of childhood overweight and obesity. In this study, we established a large scale cross-sectional study in Shanghai, China, which presented a new evidence for the correlation of hypertension prevalence with overweight and obesity stages in Chinese children and adolescents. Methods: A school-based cross-sectional study was conducted during February to December 2009 in Shanghai, China, including total 78,114 children and adolescents. Body weight, height, waist circumference (WC) and blood pressure (BP) were measured. Overweight and obesity were defined according to sex-and age-specific Chinese reference data. Results: Both SBP and DBP were very significantly increased in overweight (OW) and obese (OB) groups. With age and sex controlled, BMI and WC were independently positively correlated with SBP and DBP. The prevalence of high SBP, DBP and hypertension were markedly higher among OW and OB children than normal weight (NW) group. Odds ratios (ORs) for high SBP, high DBP and high BP were significantly greater in OW and OB children than NW group, and showed a trend increase correlating with obesity stages (all P < 0.0001). According to the increasing OR with different combination of obese status of BMI and WC, WC has a stronger influence on hypertension. The combination of BMI and WC obese shows substantially higher ORs compared with those for either BMI or WC obese alone. Conclusions: In this study on a large school-based population in Shanghai, China, BMI and WC are positively correlated with SBP and DBP. Being overweight or obese greatly increased the risk of hypertension in Chinese children and adolescents, in which WC is considered as a more sensitive indicator than BMI.