1. Division of Cardiovascular Surgery, Department of General Surgical Science, Graduate School of Medicine, Gunma University, Maebashi, Japan
2. Department of Healthcare Quality Assessment, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
3. Department of Health Policy and Management, School of Medicine, Keio University, Tokyo, Japan
4. Division of Cardiovascular Surgery, Department of Surgery, Toho University Sakura Medical Center, Sakura, Japan
5. Department of Cardiac Surgery, Graduate School of Medicine, Nagoya University, Nagoya, Japan
6. Department of Cardiovascular Surgery, Kawasaki Medical School, Kurashiki, Japan