1. Department of Urology, Vall d’Hebron Hospital, 08035 Barcelona, Spain
2. Department of Surgery, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
3. Research Group in Urology, Vall d’Hebron Research Institute, 08035 Barcelona, Spain
4. Department of Urology, Hospital Miguel Servet, IIS-Aragon, 50009 Zaragoza, Spain
5. Department of Applied Mathematics, Escuela Universitaria Politécnica La Almunia, Universidad de Zaragoza, 50100 Zaragoza, Spain
6. Statistic Unit, Vall d’Hebron Research Institute, 08035 Barcelona, Spain