PURPOSE: Patients with chronic obstructive pulmonary disease (COPD) show different response patterns to bronchodilators. We investigated associations between these different response patterns and quantitative computed tomography (CT) indices in COPD patients.
METHODS: A total of 193 stable COPD patients were analyzed retrospectively. COPD patients were classified into four phenotypes according to response patterns to salbutamol which was determined by whether the increase in forced expiratory flow volume in one second (FEV1) or forced vital capacity (FVC) exceeded current American Thoracic Society (ATS)/European Respiratory Society (ERS) criteria. Volumetric computed tomography (CT) was performed to quantify emphysema, air-trapping and large airway thickness.
RESULTS: Among 193 COPD patients, 31 (16.1%) were flow responders, 25 (13.0%) were volume responders, 39 (20.2%) were combined responders, and 98 (50.8%) were non-responders. Volume responders had a lower pre-bronchodilator FEV1 and FVC, and higher functional residual capacity (FRC) and residual volume (RV) than non-responders. Volume responders had a significantly higher CT air-trapping index than non-responders and flow-responders. CT emphysema index had a week negative correlation with post-bronchodilator FEV1 change and CT air-trapping index had a weak positive correlation with post-bronchodilator FVC change.
CONCLUSION: Volume responders have distinctive phenotypic features. Emphysema is associated with flow-responsiveness and air-trapping is associated with volume-responsiveness in COPD.
CLINICAL IMPLICATIONS: This study showed that response patterns to bronchodilators were associated with emphysema and air-trapping.
DISCLOSURE: Jae Seung Lee, Grant monies (from sources other than industry) This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare and Family Affairs, Republic of Korea (A040153) and by the Asan Institute for Life Science (07-057).; No Product/Research Disclosure Information