Additional information: IBDSL is a Dutch consortium comprising the gastroenterology departments of Maastricht University Medical Centre+ and the general district hospitals Orbis MC Sittard-Geleen and Atrium MC Heerlen. IBDSL is investigator initiated and has been funded by the consortium members. IBDSL has been approved by the Ethics Committee of the Maastricht University Medical Centre (METC 10-2-071, NL31636.068.10), and meets the ethical standards of the declaration of Helsinki. We welcome new collaborations. Applications for collaboration are first to be approved by our IBD-SL committee.