[1] Univ Penn, Perelman Sch Med, Div Pulm Allergy & Crit Care, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Palliat & Adv Illness Res PAIR Ctr, Philadelphia, PA 19104 USA
[3] Univ Michigan, Dept Internal Med, Div Pulm & Crit Care Med, Ann Arbor, MI USA
[4] Univ Michigan, Dept Epidemiol, Sch Publ Hlth, Ann Arbor, MI USA
[5] VA Ann Arbor Healthcare Syst, VA Ctr Clin Management Res, Ann Arbor, MI USA
[6] Univ Michigan, Inst Healthcare Policy & Innovat, Ann Arbor, MI USA