1. Department of Healthcare Quality and Safety, Gunma University Graduate School of Medicine , Gunma , Japan
2. Department of Nephrology, Kyoto University Graduate School of Medicine , Kyoto , Japan
3. Department of Nephrology, St Luke's International Hospital , Tokyo , Japan
4. Division of General Internal Medicine, Department of Medicine, Tokyo Medical University Ibaraki Medical Center , Ibaraki , Japan
5. Division of General Internal Medicine, Department of Medicine, St Luke's International Hospital , Tokyo , Japan
6. Department of General Internal Medicine, Ohta Nishinouchi Hospital , Koriyama, Fukushima , Japan