1. Centre for Health Studies and Research, University of Coimbra, 3004-512 Coimbra, Portugal
2. Faculty of Economics, University of Coimbra, 3004-512 Coimbra, Portugal
3. Superior School of Health, Polytechnic of Viana do Castelo, 4900-314 Viana do Castelo, Portugal
4. School of Health, Polytechnic of Porto, 4200-072 Porto, Portugal