Here we present a cross-sectional, school-based population study covering 110 schools from 19 districts of Shanghai with a large scale of children sample size. We found a significant correlation of children obesity with hypertension prevalence. Our study determined that 22.6% of children were in overweight or obese stage defined by BMI (19.2% defined by WC). Among them, there were significant increase on the prevalence of high SBP, DBP and hypertension. Importantly, the logistic regression analysis showed a positively strong association of obesity stages with the risk of hypertension prevalence in these children.
Being overweight or obese has become highly prevalent in Western countries and is rapidly reaching epidemic proportions in the developing countries. Obesity-related disorders, such as hypertension and diabetes, are also increasing at an alarming rate. In the study from Robert Whitaker et al., obese children under three years of age without obese parents are at low risk for obesity in adulthood, but among older children, obesity is an increasingly important predictor of adult obesity, regardless of whether the parents are obese or not .
The criteria for definition of children’s hypertension is arbitrary and to a certain extent, artificial. The normative data for BP in children and adolescents is the United States-based 2004 Task Force Report Update, which has been widely used in recent US-based or European-based studies . Another widely used normative data is the report of WHO expert committee on the Hypertension Control . But whether these standards are applicable to the children and adolescents in the other parts of the world, or the different ethnic backgrounds is unknown, since several studies already showed the difference of children’s BP between children in China and those in western countries . Therefore, in this study, we used Chinese reference standard for children’s hypertension published in 2010, which was established from eleven large scale cross-sectional BP surveys in mainland China from 2001 to 2010, covering four municipalities and seven provinces. Based on the Chinese reference, we made a more suitable evaluation on the Chinese children population and classified the children with hypertension.
Compared with the widely studied on the relation of obesity with hypertension, fewer studies were investigated the prevalence of hypertension in Chinese Children and whether it is related with children’s obesity in China. One recent study conducted Changsha city in China, showed the prevalence of hypertension among adolescents at the age of 12–17 years and found the relation with BMI . Another study also reported the correlation of hypertension with BMI in children population in Hainan province of South China . In this study, we classified the obesity stages of children both by BMI and WC, the two most widely used index for obesity. BMI is most widely used for the indicator of body fatness, but WC indicated the central fat that more likely correlates with diabetes than the association with general fat. Our results showed the overweight and obese groups have apparently higher prevalence of high DBP, high SBP and hypertension, which the obesity stages can be classified both by BMI and WC independently. Interestingly, our data also indicated that WC has a stronger influence on the hypertension, although one group reported that BMI is more sensitive indicator for the prevalence of hypertension in Beijing . Compared with general fat defined by BMI, central obesity defined by WC is the kind of excessive abdominal fat around the stomach and abdomen, which is believed to have a strong association with several health risks, such as type 2 diabetes, asthma and cardiovascular diseases. Especially, it is reported that a central distribution of body fat is associated with increased BP, independently of body mass index and insulin resistance in the middle-aged men . In our study, our finding indicated that in the childhood, the central obesity also has much more stronger association with risk of hypertension compared with general obesity.