Childhood and adolescent asthma remains a major public health concern. Obesity-related processes — including mechanical effects of adiposity and systemic inflammation — have been proposed as contributors to asthma risk and severity. Traditional anthropometric indices such as BMI capture overall body size but may not adequately reflect central adiposity. The Body Roundness Index (BRI), derived from waist circumference and height, is intended to better represent body roundness and central fat distribution and therefore may have different associations with asthma than general obesity measures.
The study aimed to investigate the association between BRI and current asthma among children and adolescents using nationally representative data from the National Health and Nutrition Examination Survey (NHANES) spanning 1999–2020.
This analysis used NHANES survey cycles from 1999 to 2020. The included sample comprised 28,789 participants aged 6–20 years. The design reported in the source is cross-sectional; exposure and outcome were assessed from the same survey visit.
BRI, calculated from waist circumference and height, served as the primary exposure variable intended to reflect central adiposity. Current asthma status was ascertained from questionnaire data in NHANES. The abstract does not provide the questionnaire wording, the timing of questions, or cutoffs used for defining BRI categories; those details were not reported in the source abstract.
Weighted multivariable logistic regression models were used to estimate the association between BRI and current asthma, accounting for the complex survey design of NHANES. Restricted cubic spline (RCS) models were applied to evaluate potential nonlinear relationships between BRI and asthma risk. Subgroup and sensitivity analyses were performed to test robustness, and weighted receiver operating characteristic (ROC) analyses compared the predictive ability of BRI with BMI z-score in fully adjusted models.
The abstract does not enumerate the specific covariates included in multivariable adjustment, the number or placement of spline knots, or the variables used for subgroup stratification; those analytic details were not reported in the source abstract.
Higher BRI was associated with greater odds of current asthma. In weighted multivariable logistic regression, the reported effect estimate for BRI was an odds ratio (OR) of 1.233 with a 95% confidence interval (CI) of 1.158–1.313 and p < 0.001. This indicates that, per the unit or scaling of BRI used in the models, increased BRI was linked to higher odds of asthma in this population.
Restricted cubic spline analysis suggested a nonlinear association between BRI and current asthma. The abstract reports the presence of nonlinearity but does not provide the shape of the curve, inflection points, or the range of BRI values at which risk accelerated. Those specifics were not reported in the source abstract.
Weighted ROC analyses compared BRI with BMI z-score in fully adjusted models. The abstract states that BRI and BMI z-score demonstrated comparable discriminative performance and that there was no significant difference in the area under the curve (AUC). Exact AUC values, confidence intervals for AUCs, and statistical test details for the comparison were not reported in the abstract.
Strengths evident from the abstract:
Limitations based on the abstract and information not reported:
In this NHANES-based cross-sectional analysis of children and adolescents, higher BRI was positively associated with current asthma (OR 1.233, 95% CI 1.158–1.313). There was evidence of a nonlinear relationship between BRI and asthma, and BRI performed comparably to BMI z-score in discriminative analyses. The authors conclude that elevated BRI may be linked to increased asthma prevalence in youth and highlight the need for future prospective studies.
Clinically, these findings support attention to central adiposity as a potential correlate of asthma in pediatric populations. However, given cross-sectional data, clinicians and researchers should interpret associations cautiously and prioritize longitudinal data to determine whether central adiposity precedes asthma development.
The authors recommend prospective studies to clarify temporal relationships and to investigate underlying biological mechanisms linking central adiposity (as captured by BRI) and asthma. Future reports should also provide detailed covariate adjustment sets, explicit definitions for asthma ascertainment, the full shape and thresholds from spline analyses, and the numerical AUC results for comparative predictive performance.