1. Department of Gastroenterology and Hepatology, Franciscus Gasthuis and Vlietland , Rotterdam , the Netherlands
2. Department of Gastroenterology and Hepatology, Erasmus MC , Rotterdam , the Netherlands
3. Department of Public Health, Erasmus University Medical Centre , Rotterdam , the Netherlands
4. Department of Gastroenterology and Hepatology, Amphia Hospital , Breda , the Netherlands
5. Department of Gastroenterology and Hepatology, IJsselland Hospital , Capelle aan de IJssel , the Netherlands
6. Department of Gastroenterology and Hepatology, Albert Schweitzer Hospital , Dordrecht , the Netherlands
7. Department of Gastroenterology and Hepatology, Ikazia Hospital , Rotterdam , the Netherlands
8. Department of Gastroenterology and Hepatology, Maasstad Hospital , Rotterdam , the Netherlands
9. Department of Gastroenterology and Hepatology, Reinier de Graaf Gasthuis , Delft , the Netherlands
10. Department of Statistics and Education, Franciscus Gasthuis and Vlietland , Rotterdam , the Netherlands
11. Department of Genetics, University Medical Centre Groningen, University of Groningen , Groningen , the Netherlands
12. Crohn & Colitis NL , Woerden , the Netherlands