[1] Good Shepherd Penn Partners, Dept Speech Pathol, Philadelphia, PA USA
[2] Cleveland Clin, Dept Pulm Med, Cleveland, OH 44106 USA
[3] Cleveland Clin, Dept Crit Care Med, Resp Inst, Cleveland, OH 44106 USA
[4] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Div Pulm Allergy & Crit Care Med, Perelman Sch Med, Philadelphia, PA 19104 USA
[6] Univ Penn, Palliat & Adv Illness Res Ctr, Perelman Sch Med, Philadelphia, PA 19104 USA
[7] Natl Hlth Serv Greater Glasgow & Clyde, Glasgow Royal Infirm, Glasgow, Lanark, Scotland
[8] Univ Glasgow, Sch Med Dent & Nursing, Glasgow, Lanark, Scotland