Systematic review: the potential influence of mesalazine formulation on maintenance of remission in Crohn's disease.

To evaluate the effectiveness of pH 6-/pH 7-dependent and controlled-release mesalazines in maintaining medically and surgically induced Crohn's disease remission. A systematic search identified 13 randomized controlled trials (RCTs). The rate of symptomatic relapse (Crohn's disease activity index >150, or an increase in baseline by at least 60-100 points) was extracted from each randomized controlled trial. Pooled odds ratios (OR), the number needed to treat (NNT), and percentage therapeutic benefit (absolute risk reduction) were calculated. Treatment with pH 7-dependent mesalazine significantly reduced the risk of relapse in patients with either surgically [OR 0.28; 95% confidence interval (CI) 0.12-0.65; P = 0.0032] or medically induced remission (OR 0.38; 95% CI 0.17-0.85; P = 0.0113). However, treatment with controlled-release mesalazine and pH 6-dependent mesalazine failed to show any significant advantage over placebo. The NNT to maintain surgically or medically induced remission was lowest for pH 7-dependent mesalazine (NNT = 4 and 5, respectively; NNT = 15 and 16 for controlled-release mesalazine and NNT = 11 and 23 for pH 6-dependent mesalazine). Therapeutic benefit was highest for pH 7-dependent mesalazine (surgical = 30.6%, medical = 22.8%). This compared with 6.9% (surgical) and 6.4% (medical) for controlled-release mesalazine, and 9.8% and 4.4%, respectively, for pH 6-dependent mesalazine. Further trials of pH 7-dependent mesalazine formulations are warranted in the maintenance of remission in Crohn's disease.