Structural dysanapsis of central airways is linked to inhalant allergen load in patients with asthma: A computed tomography-based analysis from the Hi-CARAT study

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Introduction: Dysanapsis, a structural disproportion in which airways are small relative to lung size, has been identified as a risk factor for obstructive lung diseases, but its clinical significance in asthma remains unclear. This study aimed to evaluate dysanapsis on chest computed tomography (CT) and investigate its association with allergen sensitization.

Methods: A total of 159 asthmatic patients from the Hi-CARAT cohort without visible emphysema were evaluated. Allergen sensitization was assessed by the Multiple Allergen Simultaneous Test (MAST)-33. The cumulative allergen sensitization score (CASS) was calculated as the sum of class values: inhalant (iCASS, 18 allergens) and food (fCASS, 15 allergens). Dysanapsis was assessed by the CT-derived airway-to-lung ratio (ALR4), defined as the geometric mean of airway luminal diameters at four central sites divided by the cubic root of total lung volume. Principal component analysis (PCA) was also performed including inhalant allergen and serum total IgE levels.

Results: Compared with iCASS = 0 (G1), patients with the highest iCASS (G4) showed significantly smaller tracheal and truncus intermedius areas (228.9 vs 258.9 mm², P = 0.003; 92.8 vs 105.4 mm², P = 0.010). ALR4 was also significantly lower in G4 than in G1 (0.0809 vs 0.0865, P = 0.004). In contrast, fCASS categories showed no significant association with airway size or ALR4. PCA showed that patients with the highest iCASS displayed broader sensitization across indoor, pollen, and fungal allergens.

Conclusions: Inhalant allergen sensitization, but not food sensitization, was associated with dysanapsis, particularly narrowing of the central airways, in asthma.