1. Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, Japan;
2. Department of Medicine, Onoda City Hospital, Onoda, Japan;
3. Department of Medicine, Masuda Red Cross Hospital, Masuda, Japan;
4. Department of Medicine, Yamaguchi Saiseikai Hospital, Yamaguchi, Japan;
5. Department of Medicine, Shuto Hospital, Yanai, Japan