Department of Emergency and Critical Care Medicine, Nippon Medical School Musashi Kosugi Hospital, 1-396 Kosugi-cho, Kawasaki-shi, Kanagawa 2118533, JapanDepartment of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan