[1] Med Univ S Carolina, Dept Med, Div Pulm & Crit Care Med, Charleston, SC 29425 USA
[2] Ralph H Johnson Vet Aff airs Hosp, Hlth Equ & Rural Outreach Innovat Ctr, Charleston, SC USA
[3] Boston Healthcare Associates, Boston, MA USA
[4] Kaiser Permanente So Calif, Dept Res & Evaluat, Pasadena, CA 91101 USA
[5] Integrated Diagnost Inc, Seattle, WA USA
[6] Johns Hopkins Univ, Dept Med, Div Pulm & Crit Care Med, Baltimore, MD USA
[7] Univ Penn, Dept Med, Pulm Allergy & Crit Care Div, Perelman Sch Med, Philadelphia, PA 19104 USA