Date Published:
Oct 08Abstract:
Rationale and Objectives: Asthma is associated with chronic airflow obstruction (CAO). Our goal was to assess the association of computed tomographic (CT) measures of airway wall volume (WV) and lumen volume (LV) with the forced expiratory volume in one second (FEV1) and CAO in smokers with childhood-onset asthma (CA). Methods: We analyzed clinical, lung function, and volumetric CT airway volumes data from 7,266 smokers including 590 with CA. Small WV and small LV of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small WV, small LV, FEV1 and CAO (post-bronchodilator FEV1/forced vital capacity ratio <0.7) using linear and logistic models. Measurements and Main Results: CA subjects had smaller WV and LV than those without CA (mean ± SD, 371.3 ± 92.5mm3 vs. 388.7 ± 94.0mm3, P<0.0001; 230.8 ± 76.9 mm3 vs. 257.4 ± 80.9mm3, P<0.0001). Among CA subjects, those with the smallest WV and LV had the lowest FEV1 and greatest odds of CAO. A similar tendency was seen in those without CA. When comparing these 2 groups, small WV and small LV were more strongly associated with FEV1 (for WV, β [95%CI] -331ml [-488 - -174] vs. -244ml [-294 - -194]; for LV, -534ml [-669 - -398] vs. -435ml [-485 - -386] and CAO (Odds ratio 2.10 (1.27-3.46) vs. 2.02 [1.72-2.36]; 4.32 [2.64-7.08] vs. 3.55 [3.00-4.19], respectively) among CA subjects in multivariate models. Conclusion: In smokers with CA smaller airways are associated with reduced lung function and chronic airflow obstruction.