Study population

A retrospective study was performed including patients from four tertiary referral centres within the INITIative Irish IBD research network (www.initiativeibd.ie).

Consecutive hospitalised patients receiving rescue IFX for corticosteroid steroid-refractory ASUC, defined by Truelove and Witts criteria, from January 2010 to September 2017 were included. Outpatients with corticosteroid-refractory UC receiving IFX were not included. Patients with a diagnosis of IBD-unclassified (IBD-U) at the time of IFX initiation, which was subsequently confirmed as Crohn’s during follow-up, were excluded. In instances where a patient had a further UC-related admission during the study follow-up period, only data from their index presentation where IFX rescue therapy was administered were considered in analyses.

UC was diagnosed based on standard clinical, endoscopic and histologic criteria. Clinical and laboratory variables were collected at time of admission and time of receipt of IFX rescue therapy. The use of AD IFX induction entered routine clinical practice in Ireland from 2014 onwards. Consequently, patients with ASUC, receiving SD IFX induction from 2014 onwards, may have differed in their baseline characteristics to those receiving treatment prior to 2014 where all ASUC patients received SD IFX induction. For this reason patients receiving SD IFX induction were subdivided into two groups, based on time of receipt IFX rescue therapy: SD¹ from January 2010 to December 2013 and SD² from January 2014 to September 2017.