1. Department of Pediatrics and Adolescent Medicine; University Hospital Rigshospitalet; Copenhagen Denmark
2. Department of Pediatrics; Aarhus University Hospital; Aarhus Denmark
3. Department of Pediatric Hematology and Oncology; H. C. Andersen Children's Hospital; Odense University Hospital; Odense Denmark
4. Department of Pediatrics; Aalborg University Hospital; Aalborg Denmark
5. Department of Pediatric and Adolescent Medicine; Turku University Hospital; Turku Finland
6. Department of Pediatrics; Astrid Lindgrens Hospital; Stockholm Sweden
7. Department of Pediatrics; University Hospital North Norway; Tromsø Norway
8. Section of Biostatistics; Department of Public Health; University of Copenhagen; Copenhagen Denmark
9. Institute of Clinical Medicine, The Faculty of Medicine; University of Copenhagen; Copenhagen Denmark