[1] Univ Alabama Birmingham, UAB Lung Hlth Ctr, Div Pulm Allergy & Crit Care Med, Birmingham, AL 35294 USA
[2] Univ Colorado, Dept Epidemiol, Aurora, CO USA
[3] Harvard Univ, Brigham & Womens Hosp, Sch Med, Div Pulm & Crit Care Med, Boston, MA 02115 USA
[4] Harbor UCLA Med Ctr, Los Angeles Biomed Res Inst, Torrance, CA 90509 USA
[5] Univ Alabama Birmingham, Dept Prevent Med, Birmingham, AL 35294 USA
[6] Univ Alabama Birmingham, Dept Radiol, Birmingham, AL 35294 USA
[7] Harvard Univ, Brigham & Womens Hosp, Sch Med, Channing Div Network Med, Boston, MA 02115 USA
[8] Natl Jewish Hlth, Div Pulm & Crit Care, Denver, CO USA
[9] Birmingham VA Med Ctr, Birmingham, AL USA