1 Amsterdam Gastroenterology, Endocrinology, Metabolism, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
2 Tytgat Institute and Department of Gastroenterology and Hepatology, Amsterdam UMC Locatie AMC, Amsterdam, North Holland, The Netherlands.
3 Amsterdam Gastroenterology, Endocrinology, Metabolism, Amsterdam University Medical Centers, Amsterdam, The Netherlands k.f.vandegraaf@amsterdamumc.nl.