Skeletal Muscle Mass and Visceral Fat are Independently Associated with Poorly Controlled Asthma in Children with Obesity: A Cross-Sectional Study.

PURPOSE: The role of body composition-particularly skeletal muscle mass and visceral fat-in asthma control among children with obesity remains unclear. We compared body composition between children with obesity with and without asthma and examined associations with asthma control.

PATIENTS AND

METHODS

We enrolled 191 children with obesity aged 6-14 years (85 with asthma, 106 without). Skeletal muscle mass (SMM)-to-body weight (WT) ratio and visceral fat area (VFA) were measured by multi-frequency bioelectrical impedance analysis. Poorly controlled asthma was defined using validated cut-points: Childhood Asthma Control Test ≤12 (ages 4-11) and Asthma Control Test ≤15 (ages ≥12). Variables were screened by least absolute shrinkage and selection operator logistic regression; the model was assessed by receiver operating characteristic curve, calibration, and decision-curve analyses.

RESULTS

The obese-asthma group had lower SMM/WT than the simple-obesity group (30.17% vs 31.51%, P<0.001); VFA did not differ significantly (P=0.051). Among children with obese-asthma, the poorly controlled group showed lower SMM/WT (P=0.002) and higher VFA (P=0.011). In multivariable analysis, SMM/WT (OR=0.664 per 1%, 95% CI 0.497-0.889, P=0.006), VFA (OR=1.014 per 1 cm2, 95% CI 1.001-1.028, P=0.034), maximal mid-expiratory flow (MMEF) percent predicted (OR=1.073, 95% CI 1.007-1.143, P=0.029), and extracellular water to total body water ratio (ECW/TBW) (OR=1.719 per 0.01, 95% CI 1.000-2.956, P=0.050) were independently associated with poorly controlled asthma. The area under the curve (AUC) was 0.807 (95% CI 0.709-0.905; sensitivity 76.9%, specificity 75.8%; mean absolute error 0.027).

CONCLUSION

Lower SMM/WT, higher VFA, higher MMEF percent predicted, and higher ECW/TBW were independently associated with poorly controlled asthma in children with obesity. The four-variable model showed good discrimination (AUC=0.807). These exploratory associations require prospective validation before clinical application.