1. Clinical Epidemiology and Biostatistics Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, Hotel de Pacientes 7a Planta, C/As Xubias de Arriba, 84, 15006 A Coruña, Spain
2. Nurse Center of Saude Carballeira, Orense, Spain