摘要Background The age of onset of hypertension(HTN)is decreasing,and obesity is a significant risk factor.The prevalence and racial disparities in pediatric HTN and the association between body composition and blood pressure are insufficiently studied.This study aimed to evaluate the prevalence of HTN in Chinese and American children and adolescents and to assess the relationship between various body composition indices and HTN.Methods Seven thousand,five hundred and seventy-three Chinese and 6239 American children and adolescents aged 8-18 years from the 2013-2015 China Child and Adolescent Cardiovascular Health study and the 2011-2018 National Health and Nutrition Examination Surveys were analyzed.Blood pressure and body composition(fat and muscle)were measured by trained staff.The crude prevalence and age-standardized prevalence rate(ASPR)of primary HTN and its subtypes[isolated systolic hypertension(ISH)and isolated diastolic hypertension(IDH)]were calculated based on 2017 American Academy of Pediatrics guidelines.Multivariable-adjusted linear regression coefficients and odds ratios(ORs)were calculated to assess the associations of body composition indicators with HTN,ISH and IDH.Results The ASPR of HTN was 18.5％in China(CN)and 4.6％in the United States(US),whereas the obesity prevalence was 7.4％and 18.6％,and the population attributable risk of HTN caused by overweight and obesity was higher in the US than in CN.Increased fat mass,muscle mass and body fat percentage mass were associated with a higher risk of HTN in both countries.The percent of muscle body mass had a protective effect on HTN and ISH in both countries[HTN(CN:OR=0.83,95％CI=0.78-0.88;US:OR=0.72,95％CI=0.64-0.81);ISH(CN:OR=0.87,95％CI=0.80-0.94;US:OR=0.71.95％CI=0.62-0.81)],and the protective effect was more common among children and adolescents with high levels of physical activity.Conclusions The burden of HTN in Chinese children and adolescents was substantial and much greater than that in the US,and the contribution of obesity to HTN was higher in the US than in CN.Augmenting the proportion of muscle mass in body composition has a protective effect against HTN in both populations.Optimizing body composition positively influences blood pressure in children and adolescents,particularly those with high-level physical activity.