1. Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
2. Department of Medical Sciences, Gastroenterology Research Group, Uppsala University, Uppsala, Sweden
3. Department of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
4. Department of Statistics, Örebro University, Örebro, Sweden
5. Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden