Long-term Efficacy and Safety of Azathioprine in Ulcerative Colitis

Background and aims: Azathioprine (AZA) is an established treatment for ulcerative colitis (UC). However, controversy exists regarding its efficacy in inducing and maintaining clinical remission, and long-term data are lacking. We studied the effectiveness of AZA in a large cohort of UC patients treated in a single center. Methods: All UC patients treated with AZA were identified from a prospective electronic database. We assessed response to therapy at 4 months and sustained clinical benefit at the last point of follow-up. We also examined predictors of response and sustained clinical benefit, as well as outcomes in those treated with AZA for >5 years. Results: The study included 255 patients. At 4 months, 207 (81.2%) of 255 patients were still on AZA and 163 (63.9%) had responded to therapy. At the last point of follow-up 164 (64.3%) patients were still receiving AZA, of whom 154 (60.4%) achieved sustained clinical benefit. This effect was durable among 71 patients who received AZA for >5 years, with 61 (85.9%) considered to have achieved sustained clinical benefit. Twenty-six patients required admission to hospital for an exacerbation during AZA treatment, 20 patients ultimately required biologic therapy, and 21 underwent colectomy. Only two (2.8%) of 71 patients receiving AZA for >5 years needed to escalate to a biologic therapy, and only one (1.4%) required a colectomy. Conclusions: AZA is a safe and effective therapy in UC patients who fail 5-aminosalisylates in both the short and long term. Escalation to a biologic therapy or colectomy was unlikely among patients who were able to continue AZA therapy beyond 5 years.