[1] Oregon Hlth & Sci Univ, Ctr Policy & Res Emergencey Med, Portland, OR 97239 USA
[2] Oregon Hlth & Sci Univ, Dept Emergency Med, Portland, OR 97239 USA
[3] Univ Penn, Dept Publ Hlth & Prevent Med, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[4] Univ Penn, Dept Med Informat & Clin Epidemiol, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA