1. Public Health and Clinical Epidemiology Service—Iberoamerican Cochrane Centre, IIB Sant Pau, 08025 Barcelona, Spain
2. Department of Social Medicine and Family Health, Universidad del Cauca, Popayan 190003, Colombia
3. Anesthesiology Service, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
4. Anesthesiology Service, Xarxa Assitencial Universitària de Manresa, 08243 Barcelona, Spain
5. Orthopedic and Traumatology Surgery Service, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
6. Anesthesiology Service, Hospital de la Vall d’Hebron, 08035 Barcelona, Spain
7. Orthopedic and Traumatology Surgery Service, Hospital Universitari Vall d’Hebron, 08035 Barcelona, Spain
8. Anesthesiology Service, Hospital Clinic de Barcelona, 08036 Barcelona, Spain
9. Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBER of Epidemiology and Public Health), 28029 Madrid, Spain