[1] Osaka Med Coll, Dept Emergency Med, 2-7 Daigaku Machi, Takatsuki, Osaka 5698686, Japan
[2] Osaka Med Coll, Dept Pediat, Takatsuki, Osaka 5698686, Japan
[3] Osaka Univ, Grad Sch Med, Dept Social & Environm Med, Div Environm Med & Populat Sci, Suita, Osaka 5650871, Japan
[4] Kyoto Univ, Hlth Serv, Sakyo Ku, Kyoto 6068501, Japan
[5] Univ Penn, Perelman Sch Med, Childrens Hosp Philadelphia, Dept Anesthesia & Crit Care Med & Pediat, Philadelphia, PA 19104 USA
[6] Okayama Univ, Grad Sch Med Dent & Pharmaceut Sci, Dept Pediat, Kita Ku, Okayama 7008558, Japan
[7] Kyoto Univ, Grad Sch Med & Publ Hlth, Dept Pharmacoepidemiol, Sakyo Ku, Kyoto 6068501, Japan
[8] Osaka City Univ, Grad Sch Med, Dept Crit Care & Emergency Med, Abeno Ku, Osaka 5458585, Japan
[9] Osaka Saiseikai Senri Hosp, Senri Crit Care Med Ctr, Suita, Osaka 5650862, Japan