1. Department of Internal Medicine Niigata University Faculty of Medicine Niigata Japan
2. Kashiwazaki General Hospital and Medical Center Kashiwazaki Japan
3. Niigata Prefectural Shibata Hospital Shibata Japan
4. Niigata Prefectural Chuo Hospital Joetsu Japan
5. Niigata Medical Center Niigata Japan
6. Nagaoka Red Cross Hospital Nagaoka Japan
7. Department of Clinical Biostatistics/Clinical Biostatistics Course Graduate School of Medicine Kyoto University Kyoto Japan