Table 1 List of participating institutions.

Akashi City Hospital

Asahikawa Medical University

Asahikawa Red Cross Hospital

Ehime University Hospital

Fukuoka University Hospital

Gifu University Hospital

Graduate School of Medicine, University of the Ryukyus

Gunma University

Hakodate Municipal Hospital

Hokkaido University Hospital

Hyogo College of Medicine

Ibaraki Prefectural Central Hospital

JA Hiroshima General Hospital

Japan Red Cross Maebashi Hospital

Jichi Medical University Saitama Medical Center

Jikei University School of Medicine

Kameda Medical Center

KKR Sapporo Medical Center

Kyoto First Red-Cross Hospital

Kyushu University Hospital

Mie University Hospital

Nagasaki University Hospital

Nihon University School of Medicine

Nippon Medical School Chiba Hokusoh Hospital

Ohta General Hospital Foundation Ohta Nishinouchi Hospital

Osaka General Medical Center

Osaka University Hospital

Saga University Hospital

Saiseikai Yokohamasi Tobu Hospital

Saitama Red Cross Hospital

Sapporo City General Hospital

Seirei Mikatahara General Hospital

Sendai City Hospital

Shonan Kamakura General Hospital

Steel Memorial Muroran Hospital

Tohoku University Hospital

Tokyo Medical University, Hachioji Medical Center

Tomishiro Central Hospital

University of Occupational and Environmental Health Hospital

Wakayama Medical University Hospital