[1] George Washington Univ, Dept Emergency Med, Ctr Hlth Care Qual, Washington, DC 20052 USA
[2] George Washington Univ, Dept Hlth Policy, Ctr Hlth Care Qual, Washington, DC USA
[3] George Washington Univ, Sch Med, Washington, DC USA
[4] Ctr Studying Hlth Syst Change, Washington, DC USA
[5] Univ Penn, Ctr Evidence Based Practice, Philadelphia, PA 19104 USA