1. Department of Urology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
2. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
3. Department of Pediatric Surgery, Hyvinkää Hospital, Hospital District of Helsinki and Uusimaa, Hyvinkää, Finland
4. Department of Pediatric Surgery, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
5. Department of Urology and Medical School, Tampere University Hospital and University of Tampere, Tampere, Finland