1. Department of Respiratory Medicine, International Medical Center, Saitama Medical University, Hidaka 350-1298, Japan
2. Department of Respiratory Medicine and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
3. Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan
4. Division of Respiratory Medicine, Clinical Department of Internal Medicine, Jichi Medical University Saitama Medical Center, Saitama 330-0834, Japan