1. Division of Respiratory Medicine, Toyama Prefectural Central Hospital, Toyama, Toyama 930‑8550, Japan
2. Department of Respiratory Medicine, International Medical Center, Saitama Medical University, Hidaka, Saitama 350‑1298, Japan
3. Department of Respiratory Medicine, Jichi Medical University, Saitama Medical Center, Saitama, Saitama 330‑8503, Japan
4. Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Eiheiji, Fukui 910‑1193, Japan