1. Department of Medicine, Division of Pulmonary Medicine, Keio University School of Medicine, Tokyo, Japan;
2. Department of Respiratory Medicine, Saitama Medical University, Moroyama-machi, Japan;
3. Division of Pulmonary Medicine, Department of Medicine, Tokai University School of Medicine, Isehara-shi, Japan;
4. Center for General Internal Medicine and Education, Keio University School of Medicine, Tokyo, Japan