[1] Univ Navarra Clin, Dept Pulm, Pamplona 31200, Spain
[2] Univ Navarra Clin, Dept Biochem & Genet, Pamplona 31200, Spain
[3] Univ Pittsburgh, Med Ctr, Div Pulm Allergy & Crit Care Med, Pittsburgh, PA USA
[4] Univ Pittsburgh, Med Ctr, Dept Epidemiol, Pittsburgh, PA USA
[5] Harvard Univ, Brigham & Womens Hosp, Sch Med, Dept Pulm, Boston, MA 02115 USA