1. Department of Paediatric Surgery and Orthopaedics, Turku University Hospital, Turku, Finland
2. Department of Paediatric Surgery and Orthopaedics, University of Turku Faculty of Medicine, Turku, Finland
3. Department of Paediatric Surgery, KYS, Kuopio, Finland
4. Department of Biostatistics, University of Turku, Turku, Finland
5. Department of Biostatistics, Turku University Hospital, Turku, Finland
6. Department of Paediatrics, Kuopio University Hospital, Kuopio, Finland
7. Department of Paediatric Surgery, Kuopio University Hospital, Kuopio, Pohjois-Savo, Finland
8. Department of Information Services, National Institute for Health and Welfare, Helsinki, Finland
9. Department of Neurobiology, Karolinska Institute, Stockholm, Stockholm County, Sweden
10. Department of Paediatric Surgery, Tampere University Hospital, Tampere, Finland
11. Department of Medicine, Tampere University Faculty of Medicine, Tampere, Finland