1. Juntendo University, Department of General Medicine, Bunkyō, Tokyo, Japan
2. Shimane University Hospital, General Medicine Center, Department of General Medicine, Izumo City, Shimane, Japan; University of Michigan Medical School, Department of Medicine, Ann Arbor, Michigan, United States of America
3. Nerima Hikarigaoka Hospital, Division of General Medicine, Tokyo, Japan; Dokkyo Medical University Hospital, Department of Diagnostic and Generalist Medicine, Mibu, Shimotsuga, Tochigi, Japan