1. Department of Pediatrics and Adolescent Medicine and Medical Research Center, Oulu University Hospital, Oulu, Finland
2. Research Unit of Clinical Medicine, University of Oulu, Oulu, Finland
3. Department of Paediatrics and Adolescent Medicine, Turku University Hospital and University of Turku, Turku, Finland
4. Research Service Unit, Oulu University Hospital, Oulu, Finland
5. Department of Pediatrics, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland