1. Nursing Department, Faculty of Nursing, University of Valladolid, 47005 Valladolid, Spain
2. Health Service of Castilla y León (Sacyl), 47007 Valladolid, Spain
3. East-Valladolid Primary Care Management (Sacyl), 47010 Valladolid, Spain
4. Unit for Active Coping Strategies for Pain in Primary Care, 47011 Valladolid, Spain
5. Institute of Applied Ophthalmobiology (IOBA), University of Valladolid, 47011 Valladolid, Spain
6. Department of Health Sciences, University of Burgos, 09001 Burgos, Spain
7. Emergency Medical Service of Castilla y León (Sacyl), 47007 Valladolid, Spain