[1] Univ Penn, Perelman Sch Med, Pulm Allergy & Crit Care Div, Dept Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[3] Univ Penn, Perelman Sch Med, Dept Phys Med & Rehabil, Philadelphia, PA 19104 USA
[4] Philadelphia Vet Affairs Med Ctr, Philadelphia, PA USA
[5] Massachusetts Gen Hosp, Dept Med, Pulm & Crit Care Unit, Boston, MA 02114 USA
[6] Intermt Med Ctr, Div Pulm & Crit Care Med, Dept Med, Murray, UT USA
[7] Brigham Young Univ, Dept Psychol, Provo, UT 84602 USA
[8] Brigham Young Univ, Ctr Neurosci, Provo, UT 84602 USA
[9] Univ Pittsburgh, CRISMA Ctr, Dept Crit Care Med, Pittsburgh, PA USA
[10] Univ Pittsburgh, Dept Hlth Policy & Management, Pittsburgh, PA USA