Long-term safety and effectiveness of azathioprine in the management of inflammatory bowel disease: A real-world experience

Abstract

Background and aim: Azathioprine (AZA) forms the cornerstone for maintenance of sustained remission in inflammatory bowel disease (IBD). There is apprehension regarding the long-term effectiveness and safety of AZA in IBD. We present our experience with AZA use and outcomes in a cohort of IBD patients followed up over a long period of time.

Methods: Records of 507 IBD patients under treatment at a single, tertiary care center in south India between 2013 and 2022 were evaluated retrospectively. Long-term compliance, tolerance, clinical outcome at the point of last follow-up, type and duration to the onset of adverse events, and subsequent amendment to treatment with regard to AZA were analyzed.

Results: Of 507 patients with IBD, 320 patients (207 Crohn's disease [CD], 113 ulcerative colitis [UC]) who received AZA were included. The median follow-up was 41 months (interquartile range 15.5-77.5). Total duration of exposure was 1359 patient-years with median usage of 33 months. Of the patients, 26.9% received AZA for >5 years. Mean initiation and maximum doses of AZA were 0.97 and 1.72 mg/kg/day. Among the participants, 20.6% experienced side effects, including myelotoxicity (7.2%) and gastrointestinal intolerance (5.6%). Six patients developed malignancy. Among the side effects, 39.4% of side effects were dose-dependent. Among the patients, 38.1% had relapses requiring pulse corticosteroid therapy, and 16.2% had more than one relapse after commencement of AZA. AZA was continued till the last follow-up in 76.5%. Among the patients, 49.7% (UC 51.3, CD 48.8) attained durable remission without biologics, and 5.3% continued to have active disease.

Conclusion: AZA is safe and effective in the long-term in IBD. Effectiveness, tolerance, and compliance with AZA are well sustained beyond 5 years of usage and comparable between UC and CD.

Keywords: adverse events; azathioprine; inflammatory bowel disease; long‐term effectiveness; tolerance.

Figure 1

Type of intervention on encountering azathioprine‐related adverse event. (), Ulcerative colitis; (), Crohn's disease.

Figure 2

Reasons for discontinuation of azathioprine. (), Ulcerative colitis; (), Crohn's disease.

Figure 3

Outcome of azathioprine (AZA)‐exposed patients at the point of last follow‐up. (), Ulcerative colitis; (), Crohn's disease. ASA, aminosalicylates.

Figure 4

Survival curve of patients who withdrew azathioprine (AZA) due to “various reasons” such as adverse events, self‐discontinuation, durable remission, pregnancy, ongoing treatment for infertility, surgery, and switch‐over to biologics. Patients (n, %): Number/percentage of patients who remained on AZA at different time periods of follow‐up.

Figure 5

Flowchart of key results of the study. ASA, aminosalicylates; AZA, azathioprine; CD, Crohn's disease; IBD, inflammatory bowel disease; UC, ulcerative colitis.