[1] Univ Iowa, Dept Emergency Med, Carver Coll Med, Iowa City, IA 52242 USA
[2] Univ Iowa, Carver Coll Med, Div Crit Care, Dept Anesthesia, Iowa City, IA 52242 USA
[3] Univ Iowa, Coll Publ Hlth, Dept Epidemiol, Iowa City, IA 52242 USA
[4] Allegheny Hlth Network, Dept Emergency Med, Pittsburgh, PA USA
[5] Hennepin Cty Med Ctr, Dept Emergency Med, Minneapolis, MN 55415 USA
[6] Olive View Univ Calif Los Angeles Educ & Res Inst, Los Angeles, CA USA
[7] Univ Iowa, Inst Clin & Translat Sci, Iowa City, IA USA
[8] Univ Calif Los Angeles, Ronald Reagan Med Ctr, Los Angeles, CA USA
[9] Univ Virginia, Dept Internal Med, Charlottesville, VA USA
[10] Ctr Dis Control, Div Healthcare Qual Promot, Atlanta, GA USA
[11] Ctr Dis Control, Div Preparedness & Emerging Infect, Atlanta, GA USA