1 German Paediatric Pain Centre, Children's and Adolescents' Hospital, Datteln, Germany.
2 Department of Children's Pain Therapy and Paediatric Palliative Care, Faculty of Health, School of Medicine, Witten/Herdecke University, Witten, Germany.
3 Faculty of Business, CareTech OWL University of Applied Sciences Bielefeld, Bielefeld, Germany.
4 Center for Pain Therapy for Young People, Garmisch-Partenkirchen, Germany.
5 Techniker Krankenkasse, Hamburg, Germany.
6 PedScience Research Institute, Datteln, Germany.