1. Pain Clinic, Complejo Hospitalario Universitario de Ourense (CHUO), Ourense, Spain
2. Pain Clinic, Hospital Universitario 12 de Octubre, Madrid, Spain
3. Pain Clinic and Department of Anesthesiology, Hospital San Juan, Alicante, Spain
4. Department of Anesthesiology, Hospital Civil (Complejo Hosp. Regional Carlos Haya), Málaga, Spain
5. Medical Department, Mundipharma, S.L., Madrid, Spain
6. Pain Clinic, Consorci Hospital General Universitari de València, Valencia, Spain
7. Department of Psychology, University of Valencia, Valencia, Spain