1. Department of Pulmonary and Critical Care Medicine Wonkwang University, Sanbon Hospital, Gunpo, Korea.
2. Department of Pulmonary and Critical Care Medicine, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Office of Health Technology Evaluation, National Evidence-Based Healthcare Collaborating Agency, Seoul, Korea.