1. Faculty of Medicine, University of Porto, Porto, Portugal.
2. Department of Community Medicine, Information and Decision in Health, Faculty of Medicine, University of Porto, Porto, Portugal.
3. Department of Stomatology, São João University Hospital Center, Porto, Portugal.
4. Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal.
5. Department of General Surgery, São João University Hospital Center, Porto, Portugal.