P546 Minimal risk of lymphoma despite long term use of azathioprine in patients with Inflammatory Bowel Disease: a longitudinal cohort analysis from Northern India

Abstract

Abstract Background Thiopurines are widely used to maintain remission in both ulcerative colitis (UC) and Crohn’s Disease (CD). Reported effectiveness and tolerability rates have been variable across studies. Moreover, there are only sparse data in the Asian population regarding the long-term efficacy and safety of azathioprine (AZT). Methods Records of 5351 patients followed up at IBD clinic, All India Institute of Medical Sciences, New Delhi from 2004–2020 were evaluated retrospectively. Azathioprine efficacy was defined as no requirement of surgery, hospitalizations, anti TNFs agents, and minimum steroid (≤1 course in 2 years) requirement on follow-up. Safety was evaluated in terms of long-term adverse events and the development of malignancy. Results Of 5351 patients with IBD, 1093 who received AZT for > 3 months (UC=788 [proctitis-1.9%, left-sided colitis-44.9%, pancolitis-53.1%], CD=305 [inflammatory-42.6%, stricturing-46.9%, fistulizing-10.5%]) were included (60.8%-males; mean age at disease onset-31.69±12.34 years) (Table1). Follow-up and treatment duration on AZT were 7(4–12) years and 39.41±40.27 months respectively. Mean initiation and maintenance dose of AZT was 1.09±0.45 mg/kg and 94.82±21.29, respectively. One,3,5, and 10 years relapse free survival was 85%,79%,76%, and 64%; 87%, 82%, 79% and 72%; and 78%, 72%, 68% and 61% in overall cohort, UC and CD patients, respectively (Log-rank P=0.001 between UC and CD). Three hundred fifty-nine [UC:249(31.6%); CD:110(36.07%); P=0.158] patients developed adverse events (AE), commonest was myelosuppression (23.42%) followed by gastrointestinal intolerance (2.97%), flu like illness (1.7%), and arthralgia/myalgia (1.37%) (Table 2). Myelosuppression was the commonest cause of AZT withdrawal. No patient (including 254 patients on AZT for ≥5 years) developed lymphoma or non-melanoma skin cancer. Adverse events free course in entire cohort, and in UC and CD are shown in fig.1 and 2 respectively. Conclusion Long-term Azathioprine monotherapy in patients with IBD is safe with minimal risk of lymphoma and non-melanoma skin cancer.