1 Department of Urology, University Hospital "Carl Gustav Carus", Dresden University of Technology, Dresden, Germany. Michael.Froehner@uniklinikum-dresden.de.
2 Department of Medical Statistics and Biometry, University Hospital "Carl Gustav Carus", Dresden University of Technology, Dresden, Germany.
3 Department of Urology, University Hospital "Carl Gustav Carus", Dresden University of Technology, Dresden, Germany.