A systematic review of the clinical effectiveness of azathioprine in patients with ulcerative colitis

To clarify the effectiveness and safety of azathioprine (AZA) and 6-mercaptopurine (6MP) in the induction and maintenance of remission in ulcerative colitis (UC) by using a systematic review of published studies. Studies were searched for from within the 1966 to March 2003 MEDLINE database, Cochrane Library 2003 issue 1, and the 1981 to March 2003 Japana Centra Revuo Medicina database. References from published studies and reviews were also obtained. Randomized, placebo-controlled trials of oral AZA or 6MP therapy in adult patients with active or quiescent UC were included. Ratios for the induction and maintenance of remission, the steroid-sparing effect, and the incidence of adverse drug reactions (ADRs) were compared and evaluated between the two study arms and expressed by the odds ratio (OR) specific for the individual studies and the meta-analytic summary for the OR. We could find no randomized controlled trial for 6MP therapy. However, four clinical trials for AZA therapy were included in this meta-analysis. For the induction of remission, the pooled OR of the response to AZA therapy compared with placebo in active UC was 1.45 (95% Confidence Interval (CI): 0.68 to 3.08). For the maintenance of remission, the pooled OR for AZA therapy was 2.26 (95% CI: 1.27 to 4.01). The number needed to treat (NNT) to prevent one recurrence was 6 patients. The pooled OR for AZA therapy's ADRs compared with placebo was 2.11 (95 % CI: 0.92 to 4.84). From the viewpoint of effectiveness and safety, this meta-analysis suggests that AZA might be useful in the maintenance of remission in UC patients.