1. Cochrane Associate Centre of Madrid; Madrid Spain
2. Clinical Biostatistics Unit; Hospital Universitario Ramón y Cajal (IRYCIS). CIBER Epidemiology and Public Health (CIBERESP); Madrid Spain
3. Faculty of Health Sciences; Universidad Francisco de Vitoria; Pozuelo de Alarcón Spain
4. Institute for Complementary and Integrative Medicine; University Hospital Zurich, University of Zurich; Zurich Switzerland
5. Department of Nursing and Physiotherapy; Universidad de Alcalá; Alcalá De Henares Spain
6. Julius Center for Health Sciences and Primary Care; University Medical Center Utrecht, Utrecht University; Utrecht Netherlands
7. Library; Hospital Universitario Ramón y Cajal (IRYCIS); Madrid Spain
8. Respiratory Department; Hospital Universitario Ramón y Cajal (IRYCIS); Madrid Spain
9. Respiratory Department; Hospital Universitario 12 de Octubre; Universidad Complutense Madrid; Madrid Spain