1. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;
2. Division of Gastroenterology, Karolinska University Hospital, Stockholm, Sweden;
3. Clinical and Translational Epidemiology Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA;
4. Clinical Epidemiology Division, Department of Medicine, Karolinska Institutet, Gothenburg, Sweden;
5. Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg, Sweden;
6. Department of Pediatric Gastroenterology, Queen Silvia Children's Hospital, Gothenburg, Sweden;
7. Gastrointestinal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA;
8. Division of Gastroenterology, Hepatology and Nutrition, University of Utah School of Medicine, Salt Lake City, Utah, USA;
9. Department of Pediatrics, Örebro University Hospital, Örebro, Sweden;
10. Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA;
11. Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.