1. Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
2. Department of Pediatrics, Aalborg University Hospital, Aalborg, Denmark
3. Department of Pediatric Rheumatology and Immunology, University Hospital Muenster, Muenster, Germany
4. Units of Clinical Biostatistics, Aalborg University Hospital, Aalborg, Denmark