[1] Johns Hopkins Univ, Sch Med, Dept Surg, Div Acute Care Surg, Baltimore, MD 21287 USA
[2] Johns Hopkins Univ, Sch Med, Div Gen Internal Med, Evidence Based Practice Ctr, Baltimore, MD USA
[3] Johns Hopkins Sch Med, Dept Anesthesiol & Crit Care Med, Baltimore, MD USA
[4] Johns Hopkins Univ Hosp, Duffey Pain & Palliat Care Program, Baltimore, MD 21287 USA
[5] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Policy & Management, Baltimore, MD USA