Exposing the Weaknesses: A Systematic Review of Azathioprine Efficacy in Ulcerative Colitis

Background Published trials evaluating the efficacy of 6-thioguanine anti-metabolites in the treatment of ulcerative colitis (UC) have yielded conflicting results. We performed a systematic review and meta-analysis to evaluate the clinical efficacy of 6-thioguanine anti-metabolites for the maintenance of clinical remission after standard induction with corticosteroids. Methods A comprehensive search of online databases was conducted. Only randomized controlled trials with 6-thioguanine anti-metabolites within a minimum duration of follow-up of 6 months were selected. Results Five trials were included in the meta-analysis. The pooled relative risk estimate for “success of treatment” with azathioprine (AZA) compared to 5-aminosalicylic acid or placebo was 1.42 [95% confidence interval (CI): 0.93–2.17, p = 0.109]; when only trials of a higher quality were used, a pooled relative risk estimate of 2.05 (95% CI: 1.30–3.23, p = 0.002) was obtained. Conclusions Pooled results demonstrated a modest efficacy of AZA for the treatment of ulcerative colitis. However, the use of AZA for the management of UC is not based on high-quality evidence.