1. Department of Pediatrics and Adolescent Medicine Aarhus University Hospital, and Department of Clinical Medicine Aarhus University Aarhus Denmark
2. Section of Biostatistics Department of Public Health University of Copenhagen Copenhagen Denmark
3. Department of Pediatrics and Adolescent Medicine University Hospital Rigshospitalet Copenhagen Denmark
4. Department of Pediatric Hematology and Oncology H. C. Andersen Children's Hospital Odense University Hospital Odense Denmark