1. Department of Global Public Health and Primary CareUniversity of BergenBergen Norway
2. Department of PediatricsHaukeland University HospitalBergen Norway
3. Norwegian Institute of Public HealthBergen Norway
4. Cancer Registry of NorwayOslo Norway
5. Department of ResearchStatistics NorwayOslo Norway
6. Department of Pediatric MedicineOslo University HospitalOslo Norway
7. Institute of Clinical Medicine, Faculty of Medicine, University of OsloOslo Norway