1. Pulmonology Department; Instituto de Investigaciones Sanitarias de Santiago (IDIS); Santiago de Compostela Spain
2. Division of Pulmonary; Critical Care; Allergy and Sleep Medicine; Medical University of South Carolina; Charleston South Carolina USA
3. Clinical Epidemiology Department; Instituto de Investigaciones Sanitarias de Santiago (IDIS); Santiago de Compostela Spain
4. Clinical Analysis Department; University Hospital of Santiago; Instituto de Investigaciones Sanitarias de Santiago (IDIS); Santiago de Compostela Spain