[1] Nagoya Ekisaikai Hosp, Dept Emergency Med, 4-66 Shonen, Nagoya, Aichi 4548502, Japan
[2] Massachusetts Gen Hosp, Dept Emergency Med, 125 Nashua St Boston,Suite 920, Boston, MA 02114 USA
[3] Tokyo Metropolitan Childrens Med Ctr, Dept Paediat Emergency & Crit Care Med, 2-8-29 Musashidai, Fuchu, Tokyo 1838561, Japan
[4] Harvard TH Chan Sch Publ Hlth, Dept Hlth Policy & Management, 677 Huntington Ave Boston, Boston, MA 02115 USA
[5] Univ Washington, Dept Radiol, 850 Republican St, Seattle, WA 98006 USA
[6] St Lukes Int Hosp, Dept Emergency Med, Ctr Clin Epidemiol, Chuo Ku, 3-6 Tsukiji, Tokyo 1040045, Japan