1. Department of Medical Psychology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Pediatric Surgery, Hannover Medical School, Hannover, Germany
3. Department of Pediatric Surgery, Drottning Silvias barn- och ungdomssjukhus i Goteborg, Goteborg, Sweden
4. Department of Pediatrics, University of Gothenburg Institute of Clinical Sciences, Goteborg, Sweden