1. Biomedical Research Institute of Salamanca (IBSAL), Primary Care Research Unit, The Alamedilla Health Centre, Castilla and León Health Service (SACYL), Salamanca, Spain
2. Department of Nursing and Physiotherapy, University of Salamanca, Salamanca, Spain
3. Department of Statistics, University of Salamanca, Salamanca, Spain
4. Department of Basic Psychology, Psychobiology and Behavioral Sciences Methodology, University of Salamanca, Salamanca, Spain
5. Department of Medicine, University of Salamanca, Salamanca, Spain
6. Department of Biomedical and Diagnostic Sciences, University of Salamanca, Salamanca, Spain