Airway closure during metacholine challenge is correlated to body mass index

Background and Aim: Airway closure (AC) during metacholine (MTCH) bronchial challenge is described in asthma. Aim of this retrospective study was to correlate AC during MTCH challenge with anthropometric data, functional parameters and asthma control. Methods: Forty-four consecutive patients with Asthma (GINA guidelines) 30F/14M aged 45+15 years were considered for the analysis. At the last visit 4/44 were uncontrolled (Asthma Control Test [ACT] score 17.5+4), 7/44 partially controlled (ACT 24.2+1.0) and 33/44 well controlled. Airway closure during MTCH challenge (expressed as Delta forced vital capacity (%) / Delta FEV1(%) ratio during the test), ACT, BMI, exhacerbations number, FENO, Tot IgE, eosinophils were considered Results: Respect to patient with controlled asthma, patient with partially controlled or uncontrolled asthma had higher exacerbation rate (0.5 vs 0.12 /year, p<0.04), showed similar airway closure during MTCH test (DeltaFVC/DeltaFEV1 ratio : 0.74+0.2 vs 0.69+0.2, NS; with similar forced expiratory time 5.6+1.8 vs 5.3+2.0 s, NS) but higher BMI (29.8+7.2 vs 25.4+4.8, p<0.04). Similar findings were present considering only uncontrolled patients versus controlled / partially controlled. AC during challenge was correlated with BMI (r=0.629, p<0.001) and age (r=0.376, p<0.02) on the total and also in non-obese population, whereas ACT score correlated only to BMI (r=-0.551, p<0.004). IgE levels were correlated (r=0.52, p<0,03) with Eosinophils (% and absolute value) and inversely with age (r=0.582, p<0.02). No correlation between FENO and functional parameters were observed. Conclusions: Airway closure during MTCH test is related to BMI rather than asthma control (ACT) during follow up.