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P563 Thiopurine adverse events in patients with inflammatory bowel disease in the UK: inflammatory bowel disease BioResource cohort

Y. Y. Hong*1, D. A. Withanachchi1, S. P. Aslam1, Y. Khalid1, R. Shawky1, M. Parkes1

1Gastroenterology Department, Addenbrooke's Hospital, Cambridge, UK


The Inflammatory Bowel Disease (IBD) BioResource is a research database recruiting patients with Crohn’s disease (CD), ulcerative colitis (UC) or IBD type Unclassified (IBDU) from 83 hospitals UK-wide. In total, 17 470 subjects have been recruited to date. Data have been collected on disease phenotype, treatment, adverse events and treatment response.


The aim of this study was: to describe the prevalence of adverse events related to thiopurine exposure among the IBD Bioresource cohort. A descriptive, retrospective analysis of the IBD BioResource database has been performed to determine the incidence of short- and long-term adverse events related to the use of thiopurines in the treatment of inflammatory bowel disease. All patients who have had exposure to thiopurine therapy (azathioprine or 6-mercaptopurine) were included.


In total, 10 092 (57.8%) patients within the IBD BioResource cohort have had some exposure to thiopurine therapy during their disease course, either as monotherapy or in combination with anti-TNF. 9480 patients (94.0%) have been treated with azathioprine (AZA) and 2335 patients (23.1%) have been treated with 6-mercaptopurine (6MP). Of the 9480 patients who have been treated with azathioprine, 4167 patients (44.0%) remain on this therapy. 2369 patients (24.9%) ceased azathioprine due to adverse events. Of the 2335 patients, 1723 treated with 6MP had previously been treated with AZA and been intolerant. 684 patients (29.3%) ceased 6MP due to adverse events. 951 patients (40.7%) remained on 6MP at the time of recruitment to IBD Bioresource. The most commonly reported adverse events were nausea and vomiting (9.6%), followed by deranged liver function tests (5.1%), non-specified patient intolerance (2.4%), flu like symptoms (2.3%) and abdominal pain (2.3%). The incidence of clinically serious side effects was low. Pancreatitis was reported in 2.2% of patients; and leucopoenia (total WCC <3 or neutrophil count <2) was seen in 3.7%. 83 (0.8%) patients developed lymphoma after a mean of 2.89 years on thiopurine treatment 27 out of 83 were also on anti-TNF


Thiopurines are a safe treatment option for the management of inflammatory bowel disease. In this large national UK cohort, serious clinical adverse events related to thiopurine exposure were not common. Despite this low rate of serious adverse events, thiopurines were ceased due to side effects in 25.11% of patients.