1. International Doctoral School of the Universidad Nacional de Educación a Distancia and the Joint Research Institute of the Nacional School of Health (UNED-IMIENS), Madrid 28015, Spain
2. Health Institute Carlos III, Madrid 28029, Spain
3. CIBER of Epidemiology and Public Health (CIBERESP), Madrid 28029, Spain
4. University of Alicante (UA), Alicante 03690, Spain