Toxicity profile of thiopurines in inflammatory bowel disease: a retrospective cohort analysis.

Thiopurines have proven efficacy in inflammatory bowel disease. However, their use is limited by adverse effects in a subset of patients.The present study aimed to evaluate toxicity profile and identify clinical predictive factors of thiopurine adverse effects in inflammatory bowel disease patients.A retrospective longitudinal study was conducted among inflammatory bowel disease patients treated with thiopurines. Multiple logistic regression was used to identify risk factors for thiopurine adverse effects.A total of 210 patients were enrolled in the study. Mean age at disease onset was 29.8±11.4 years. One hundred sixty-nine (169) patients had Crohn's disease, 29 had ulcerative colitis and 12 had indeterminate colitis. During a median follow-up of 28.5 ± 20 months, 56 patients (26.6%) had thiopurine-related adverse effects including digestive intolerance (n=14; 6.6%), immunoallergic reactions (n=8; 3.8%), myelotoxicity (n=25; 11.9%) and hepatotoxicity (n=8; 3.8%). Treatment withdrawal was reported in 19 patients (9%). The only independent predictive factor for thiopurine adverse effects found in this study was steroid-dependence (OR= 3.96; 95% CI: 1.07- 14.53; p= 0.038).Almost a quarter of inflammatory bowel disease patients treated with thiopurines developed adverse effects. These adverse effects lead to drug withdrawal in almost 9% of patients either as monotherapy or as in combination with biologic therapies. Steroid-dependent patients were significantly at higher risk for thiopurine-related toxicity.