Comparison of airway remodelling assessed by computed tomography in asthma and COPD.

Background: Few studies have directly compared airway remodelling assessed by computed tomography (CT) between asthma and chronic obstructive pulmonary disease (COPD). The present study was conducted to determine whether there are any differences between the two diseases with similar levels of airflow limitation under clinically stable conditions.

Methods: Subjects included older male asthmatic patients (n = 19) showing FEV(1)/FVC <70% with smoking history less than 5-pack/year. Age- and sex-matched COPD patients (n = 28) who demonstrated similar airflow limitation as asthmatic patients and age-matched healthy non-smokers (n = 13) were recruited. Using proprietary software, eight airways were selected in the right lung, and wall area percent (WA%) and airway luminal area (Ai) were measured at the mid-portion of the 3rd to 6th generation of each airway. For comparison, the average of eight measurements per generation was recorded.

Results: FEV(1)% predicted and FEV(1)/FVC was similar between asthma and COPD (82.3 ± 3.3% vs. 77.6 ± 1.8% and 57.7 ± 1.6% vs. 57.9 ± 1.4%). At any generation, WA% was larger and Ai was smaller in asthma, both followed by COPD and then controls. Significant differences were observed between asthma and controls in WA% of the 3rd to 5th generation and Ai of any generation, while no differences were seen between COPD and controls. There were significant differences in Ai of any generation between asthma and COPD.

Conclusions: Airway remodelling assessed by CT is more prominent in asthma compared with age- and sex-matched COPD subjects in the 3rd- to 6th generation airways when airflow limitations were similar under stable clinical conditions.