[1] Univ Penn, Div Pulm Allergy & Crit Care Med, Dept Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Palliat & Adv Illness Res PAIR Ctr, Philadelphia, PA 19104 USA
[3] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[4] Univ Penn, Perelman Sch Med, PAIR Ctr, Philadelphia, PA 19104 USA
[5] Univ Penn, Perelman Sch Med, Dept Biostat Epidemiol & Informat, Philadelphia, PA 19104 USA
[6] Western Hlth, Dept Physiotherapy, Melbourne, Vic, Australia
[7] Univ Melbourne, Dept Physiotherapy, Melbourne, Vic, Australia
[8] Monash Univ, Australian & New Zealand Intens Care Res Ctr, Melbourne, Vic, Australia
[9] Univ Penn, Dept Family Med & Community Hlth, Perelman Sch Med, Philadelphia, PA 19104 USA
[10] Univ Penn, Sch Arts & Sci, Dept Anthropol, Philadelphia, PA 19104 USA
[11] Univ Penn, Perelman Sch Med, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[12] Univ Penn, Perelman Sch Med, Dept Med Eth & Hlth Policy, Philadelphia, PA 19104 USA
[13] Univ Penn, Div Pulm Allergy & Crit Care Med, Philadelphia, PA 19104 USA
[14] Corporal Michael J Crescenz Vet Affairs Med Ctr, Dept Med, Div Pulm & Crit Care Med, Philadelphia, PA USA