1. Department of Internal Medicine, Marugame Medical Center , Kagawa 763-8507, Japan and Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
2. Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science , 2-5-1 Shikata-cho, Kita-ku , Okayama 700-8558, Japan
3. Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science , 2-5-1 Shikata-cho, Kita-ku , Okayama 700-8558, Japan . email: hagiya@okayama-u.ac.jp