1. Division of General Medicine, Mito Medical Center, University of Tsukuba‑Mito Kyodo General Hospital, Mito, Ibaraki 310‑0015, Japan
2. Division of Pathology, Mito Medical Center, University of Tsukuba‑Mito Kyodo General Hospital, Mito, Ibaraki 310‑0015, Japan
3. Division of Surgery, Mito Medical Center, University of Tsukuba‑Mito Kyodo General Hospital, Mito, Ibaraki 310‑0015, Japan
4. Division of Respiratory Medicine, Mito Medical Center, University of Tsukuba‑Mito Kyodo General Hospital, Mito, Ibaraki 310‑0015, Japan
5. Division of Respiratory Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8575, Japan