[1] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Dept Biostat Epidemiol & Informat, Philadelphia, PA 19104 USA
[3] Univ Penn, Wharton Sch, Philadelphia, PA 19104 USA
[4] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[5] Univ Michigan, Dept Internal Med, VA Ctr Clin Management Res, Ann Arbor, MI 48109 USA
[6] Univ Penn, Sch Nursing, NewCourtland Ctr Transit & Hlth, Philadelphia, PA 19104 USA
[7] Visiting Nurse Serv New York, Ctr Home Care Policy & Res, New York, NY USA
[8] Thomas Jefferson Univ, Sidney Kimmel Med Coll, Dept Emergency Med, Philadelphia, PA 19107 USA
[9] Hosp Univ Penn, Dept Med, Div Pulm Allergy & Crit Care Med, Philadelphia, PA 19104 USA