The association between waist-to-height ratio and asthma in U.S. children: a cross‑sectional study from NHANES 1999 to 2020

BACKGROUND: In addition to the established link between obesity and asthma, the precise role of adiposity, both total and central, as measured by waist-to-height ratio (WHtR), remains underexplored in pediatric asthma. We aimed to investigate the association between WHtR and asthma in United States (U.S.) children and adolescents. METHODS: This cross-sectional study included 34,957 participants aged 3-17 years from the National Health and Nutrition Examination Survey (NHANES, 1999-2020). Multivariable logistic regression models were used to assess the relationship between WHtR and asthma. Generalized additive models and two-piecewise logistic regression were employed to examine nonlinearity. RESULTS: A total of 5,847 (16.7%) children had asthma. Each 0.1-unit increase in WHtR was associated with a 25% higher odds of asthma (OR = 1.25, 95% CI: 1.20-1.30) after full adjustment. A nonlinear relationship was identified with an inflection point at WHtR = 0.467. Below this point, each 0.1-unit increase in WHtR was associated with a 61% increase in asthma odds (OR = 1.61, 95% CI: 1.38-1.88); above it, the increase was 18% (OR = 1.18, 95% CI: 1.11-1.24). CONCLUSION: In U.S. children and adolescents, WHtR was positively associated with asthma prevalence in a nonlinear pattern. An elevated WHtR was associated with an increased risk of asthma.