The drug-survival of low-dose thioguanine in patients with inflammatory bowel disease: a retrospective observational study

Background: Thiopurines are commonly used to treat inflammatory bowel disease but withdrawal due to side effects are common. Thioguanine has been suggested to be better tolerated than conventional thiopurines. Objectives: We studied drug-survival of low dose of thioguanine in real-life clinical practice in comparison to conventional thiopurines. Design: Retrospective observational study. Methods: All patients born 1956 and later, and who at least once started thiopurine treatment between 2006 and 2022 were included. A medical chart review was performed that noted drug-survival for every thiopurine treatment attempt. The Mantel–Cox rank test was used to test differences in drug-survival for different thiopurines. Blood chemistry analysis and faecal calprotectin levels were registered for the first 5 years of treatment. Results: In the study population, there was 379 initiated thiopurine treatments (210 for Crohn’s disease and 169 for ulcerative colitis) in 307 patients with inflammatory bowel disease (IBD). Low-dose thioguanine (median dose 11 mg; 25–75th percentile 7–19 mg) had been initiated in 31 patients. Overall, when including all thiopurine attempts, thioguanine had the longest drug-survival [Mantel–Cox rank test: thioguanine versus azathioprine p = 0.014; thioguanine versus 6-mercaptopurine (6-MP) p