1. Biocruces Bizkaia Health Research Institute , Baracaldo , Spain
2. Research Network in Health Services in Chronic Diseases (Red de Investigación en Servicios de Salud en Enfermedades Crónicas, REDISSEC), Research Unit of the Barrualde-Galdakao IHO , Galdakao , Spain
3. Department of Pneumology , Hospital Galdakao , Usansolo , Spain
4. Medicine Laboratory Department , University Hospital Santa Lucía , Cartagena , Spain