Methods: We examined a total of 100 patients with COPD and 40 patients with ACOS, who were selected based on clinical criteria. All patients underwent baseline testing, including a COPD assessment test (CAT), pulmonary function tests, and multidetector row computed tomography (MDCT) imaging. Percentage of low attenuation volume (LAV%), percentage of wall area (WA%), and percentage of total cross-sectional area of pulmonary vessels less than 5 mm2(%CSA <5) were determined using MDCT. ACOS patients were administered a fixed dose of budesonide/formoterol (160/4.5 µg, 2 inhalations; bid) for 12 weeks, after which the ACOS patients underwent MDCT to measure the same parameters.
Results: At baseline, the ACOS patients and COPD patients had a similar degree of airflow limitation, vital capacity, and residual volume. ACOS patients had higher CAT scores, WA%, and %CSA <5 than COPD patients. Compared to baseline, budesonide/formoterol treatment significantly increased the forced expiratory volume in 1 second (FEV1) and decreased the degree of airway wall thickness (WA%) in ACOS patients.
Conclusion: Our results suggest that ACOS is characterized by an airway-lesion-dominant phenotype, in contrast to COPD. Higher pulmonary microvascular density (%CSA <5) might be a characteristic feature of ACOS.