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.