Associations of body roundness index and inflammatory marker with hypertension among children and adolescents: a cross-sectional study

Hypertension in children and adolescents constitutes a critical public health challenge, which is influenced by both adiposity and inflammation pathway, but the association of newly adiposity evaluation tool and its joint influence with inflammation on hypertension in youth is not clear. This study investigates the associations between emerging adiposity metric (Body Roundness Index, BRI), Systemic Immune Inflammation Index (SII), and hypertension in a pediatric cohort from the National Health and Nutrition Examination Survey. Associations among BRI and SII with hypertension were analyzed using logistic regression models. A total of 19,073 participants (mean age 12.71 years) were included in the analysis, with 51.10% males. There was an increasing trend in inflammatory markers and the prevalence of hypertension with increasing BRI. The average BRI in this population increased from 3.10 in 1999 to 3.28 in 2011 and stabilized at 3.34 by 2020. The prevalence of hypertension decreased from 13.02% in 1999 to 8.05% in 2009 and remained at 8.16% in 2020. Higher BRI was positively correlated with increased prevalence of hypertension, particularly in the highest quartile (OR: 2.184, p < 0.001). Restricted cubic spline analysis indicated a nearly linear positive correlation between BRI and SII with the risk of hypertension. Adolescents with both high BRI and high SII faced a significantly amplified risk of hypertension (OR: 2.846, p < 0.0001). Mediation analysis indicated that SII explained 3.69% of the relationship between BRI and hypertension. Subgroup analyses showed consistent associations across sex and race. Our findings establish BRI as an anthropometric predictor of hypertension in the youth that partially operates through inflammatory mechanisms, suggesting that combined assessment of adiposity and systemic inflammation could enhance early identification of at-risk youth.