Association between body roundness index and asthma in children and adolescents: findings from NHANES 1999–2020

BACKGROUND: Childhood and adolescent asthma remains a major public health concern, and obesity may contribute through mechanical and inflammatory pathways. The Body Roundness Index (BRI), derived from waist circumference and height, may better reflect central adiposity than general body-size measures. AIM: To investigate the association between BRI and asthma in children and adolescents. SUBJECTS AND METHODS: A total of 28,789 National Health and Nutrition Examination Survey (NHANES) 1999-2020 participants aged 6-20 years were included. Current asthma was identified using questionnaire data. BRI, calculated from waist circumference and height, was used as the primary exposure. Weighted multivariable logistic regression models were used to examine the association between BRI and current asthma, and restricted cubic spline (RCS) models were applied to assess potential nonlinear associations. Subgroup and sensitivity analyses were performed to assess the robustness of the findings. Weighted receiver operating characteristic (ROC) analyses were used to compare the predictive abilities of BRI and Body Mass Index (BMI) z-score in fully adjusted models. RCS analysis suggested a nonlinear association between BRI and current asthma. In fully adjusted analyses, BRI and BMI z score showed comparable discriminative performance, with no significant difference in the area under the curve. CONCLUSIONS: Higher BRI was positively associated with current asthma among children and adolescents. Future prospective studies are warranted to clarify the temporal relationship and underlying biological mechanisms.