1. Sachs’ Children and Youth Hospital, South General Hospital, Stockholm, Sweden
2. Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
3. Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden
4. Unit of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
5. Division of Gastroenterology, Massachusetts General Hospital; Harvard Medical School, Boston, Massachusetts, USA
6. Centre for Health Equity Studies, Stockholm University/Karolinska Institutet, Stockholm, Sweden
7. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
8. Department of Pediatrics, Örebro University Hospital, Örebro, Sweden