[1] Univ Pittsburgh, Sch Med, Dept Emergency Med, Pittsburgh, PA 15261 USA
[2] Osaka Univ, Grad Sch Med, Dept Integrated Med, Div Biomed Stat, Osaka, Japan
[3] Aarhus Univ, Dept Clin Med, Aarhus, Denmark
[4] Aarhus Univ Hosp, Dept Anesthesiol & Intens Care, Aarhus, Denmark
[5] Prehosp Emergency Med Serv, Aalborg, Cent Denmark Re, Denmark
[6] Univ Penn, Perelman Sch Med, Childrens Hosp Philadelphia, Dept Anesthesiol & Crit Care Med, Philadelphia, PA USA
[7] Univ Chicago, Sch Med, Dept Med, Sect Emergency Med, Chicago, IL USA
[8] Univ Toronto, Sunnybrook Hlth Sci Ctr, Dept Med, Div Emergency Med, Toronto, ON, Canada