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, University of Tokyo, Tokyo, Japan
3. Harajuku Rehabilitation Hospital, Tokyo, Japan
4. Department of Cardiovascular Surgery, Toho University, Sakura Medical Center, Sakura, Japan
5. Department of Health Policy and Management, School of Medicine, Keio University, Tokyo, Japan